# Top 50 professional services firms in Turkey

Tamtam tracks 74 professional services firms headquartered in Turkey. This list ranks the 50 largest by number of employees on LinkedIn, led by Avukat, Serbest Muhasebeci Mali Müşavirlik Hizmetleri and KUCUKYiLMAZ Consulting Co.. Their median headcount is 471. Half of them were founded in 2003 or later. The most common headquarters are Istanbul (26) and Ankara (6).

This selection of professional services firms in Turkey includes large companies specializing in law, accounting, engineering, and IT consulting. Among them are Avukat, a legal practice with 4336 employees, and Serbest Muhasebeci Mali Müşavirlik Hizmetleri, an accounting firm with 3332 employees. Other notable firms include KUCUKYiLMAZ Consulting Co. in motor vehicle manufacturing consulting, and STM, which provides high-technology project management and engineering for defense systems.

The data shows a concentration of headquarters in Istanbul, with many firms established in the early 1980s, such as KPMG Türkiye (founded 1982) and PwC Türkiye (founded 1981). There is also a significant presence of government-affiliated entities like Türk Standardları Enstitüsü, focused on national standards, and TCDD Teknik Mühendislik ve Müşavirlik A.Ş., specializing in railroad engineering.

🇹🇷 Turkey · 50 companies · Updated Nov 12, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Avukat](https://www.tamtam.ai/c/avukat) (sanliurfaavukat.com)<br>Explore detailed information about legal services on our page | Law Practice | 🇹🇷 Istanbul | 4,336 | 2013 |
| 2 | [Serbest Muhasebeci Mali Müşavirlik Hizmetleri](https://www.tamtam.ai/c/serbest-muhasebeci-mali-musavirlik-hizmetleri) (smmmemrahkucukdeniz.com)<br>An accounting office in Istanbul providing practical solutions to tax issues for clients nationwide, focusing on communication, trust, and quality service | Accounting | 🇹🇷 Istanbul | 3,332 | 2013 |
| 3 | [KUCUKYiLMAZ Consulting Co.](https://www.tamtam.ai/c/kucukyilmaz-consulting-co) (facebook.com)<br>With 25 years of experience in the friction industry, offering assistance in compounding, process, product, and business development, representing major suppliers | Motor Vehicle Manufacturing | 🇹🇷 Istanbul | 2,363 | 2004 |
| 4 | [SMMM SAIT OZDEMIR](https://www.tamtam.ai/c/smmm-sait-ozdemir) (saitozdemir.com)<br>Offering tax consultancy, bookkeeping according to business standards, handling SGK procedures, providing financial advisory, establishing accounting systems, assisting with personal and company setup procedures | Accounting | 🇹🇷 Rasimpaşa | 2,137 |  |
| 5 | [Türk Standardları Enstitüsü](https://www.tamtam.ai/c/turk-standardlar-enstitusu) (tse.org.tr)<br>Development and enforcement of national standards for products, services, and procedures under government oversight and legal framework. | Utilities | 🇹🇷 Ankara | 1,560 | 1960 |
| 6 | [STM](https://www.tamtam.ai/c/stm) (stm.com.tr)<br>Provides high technology project management, engineering, and consultancy services for military systems, developing domestic software and platforms for defense industry procurement operations. | Defense and Space Manufacturing | 🇹🇷 Ankara | 1,537 | 1991 |
| 7 | [KPMG Türkiye](https://www.tamtam.ai/c/kpmg-turkiye) (kpmg.com)<br>Providing audit, tax, and advisory services to diverse industries with a sector-focused approach and extensive local and international expertise. | Business Consulting and Services | 🇹🇷 Istanbul | 1,446 | 1982 |
| 8 | [Ünsped Gümrük Müşavirliği ve Lojistik Hizmetler A.Ş.](https://www.tamtam.ai/c/unsped-gumruk-musavirligi-ve-lojistik-hizmetler-a-s) (ugm.com.tr)<br>Specializing in international trade logistics and customs services, the company provides quality solutions with a focus on innovation and customer satisfaction | Wholesale Import and Export | 🇹🇷 Mahmutbey | 1,412 | 1981 |
| 9 | [TCDD Teknik Mühendislik ve Müşavirlik A.Ş.](https://www.tamtam.ai/c/tcdd-teknik-muhendislik-ve-musavirlik-a-s) (tcddteknik.com.tr)<br>A government-owned engineering firm specializing in engineering, consultancy, technology, signaling, energy, certification, and measurement services in various fields | Railroad Equipment Manufacturing | 🇹🇷 Ankara | 1,361 | 2017 |
| 10 | [Yüksel Proje](https://www.tamtam.ai/c/yuksel-proje) (yukselproje.com.tr)<br>A leading provider of design, engineering, and consultancy services for various sectors worldwide, with a focus on sustainable and innovative projects | Civil Engineering | 🇹🇷 Ankara | 1,284 | 1978 |
| 11 | [PwC Türkiye](https://www.tamtam.ai/c/pwc-turkiye) (pwc.com.tr)<br>A global network providing quality assurance, advisory, and tax services with a focus on building trust and solving important issues | Professional Services | 🇹🇷 Beyoglu | 1,277 | 1981 |
| 12 | [BGTS](https://www.tamtam.ai/c/bgts) (bilgeadam.com)<br>An international technology consulting firm specializing in software development, IT consulting, business processes, QA & testing, big data, cloud, AI/ML, and cybersecurity services | IT Services and IT Consulting | 🇹🇷 Istanbul | 1,182 | 1997 |
| 13 | [Deloitte Turkey](https://www.tamtam.ai/c/deloitte-turkey) (deloitte.com.tr)<br>The company provides audit, consulting, financial advisory, risk management, tax services to public and private clients across various industries globally | Management Consulting | 🇹🇷 Istanbul | 978 |  |
| 14 | [Solmaz](https://www.tamtam.ai/c/solmaz) (solmaz.com)<br>A leading logistics service provider offering customs consultancy, international transportation, supply chain management, express courier, and insurance services with over 1,200 expert staff nationwide | Transportation, Logistics, Supply Chain and Storage | 🇹🇷 Şişli | 891 | 1978 |
| 15 | [OBSS](https://www.tamtam.ai/c/obss) (obss.tech)<br>Leader in technology consulting for a cloud-powered future, with expertise in banking, insurance, e-commerce, retail, and start-ups Strong team with offices in Europe | IT Services and IT Consulting | 🇹🇷 Istanbul | 870 | 2005 |
| 16 | [Serbest Muhasebeci Mali Müşavir](https://www.tamtam.ai/c/serbest-muhasebeci-mali-musavir)<br>Beauty institute offering a variety of treatments such as hammam, massages, manicures, pedicures, hair styling, facials, and women's waxing services | Accounting | 🇹🇷 Kestel | 711 | 2019 |
| 17 | [Özel bir danışmanlık şirketi](https://www.tamtam.ai/c/ozel-bir-dan-smanl-k-sirketi) (kml.com.tr)<br>Strategic planning, brand management, marketing, sales management, R&D, innovation, HR, supply chain, quality management, IT, corporate governance, digital transformation, corporate training | Business Consulting and Services | 🇹🇷 Istanbul | 705 | 2019 |
| 18 | [EMAY INTERNATIONAL ENGINEERING and CONSULTANCY Inc.](https://www.tamtam.ai/c/emay-international-engineering-and-consultancy-inc) (emay.com)<br>A leading engineering and consultancy firm in Turkey, offering services in transportation, buildings, and water & environment sectors with a focus on architectural and engineering projects | Design Services | 🇹🇷 Üsküdar | 704 | 1980 |
| 19 | [Data Gümrük Müşavirliği](https://www.tamtam.ai/c/data-gumruk-musavirligi) (datagumrukleme.com)<br>A logistics business that has expanded its services and branches, focusing on customer satisfaction with modern management techniques and technological infrastructure | Business Consulting and Services | 🇹🇷 Izmir | 703 | 2003 |
| 20 | [DIP](https://www.tamtam.ai/c/dip) (dip.com)<br>Specializing in Data & Analytics solutions, creating custom solutions for organizations, providing consulting services in data transformation, analysis, and management processes | IT Services and IT Consulting | 🇹🇷 Istanbul | 702 | 2012 |
| 21 | [adesso Turkey](https://www.tamtam.ai/c/adesso-turkey) (adesso.com.tr)<br>A digital transformation company with agile beliefs, employing over 10,000 people worldwide, offering custom software development and IT solutions | IT Services and IT Consulting | 🇹🇷 Istanbul | 628 | 2013 |
| 22 | [Commencis](https://www.tamtam.ai/c/commencis) (commencis.com)<br>A company specializing in experience design, software engineering, and cloud technologies, enabling enterprises to build digital experiences and strengthen customer relationships globally | Software Development | 🇹🇷 Istanbul | 542 | 2000 |
| 23 | [Academy](https://www.tamtam.ai/c/academy) (inkaik.com)<br>Specializing in HR research, selection, project-based staffing, HR consultancy, management consultancy, and payroll services with a focus on professionalism and confidentiality | Human Resources Services | 🇹🇷 Istanbul | 537 |  |
| 24 | [mediSMART Contract Research Organization](https://www.tamtam.ai/c/medismart-contract-research-organization) (medismart.com.tr)<br>Clinical Research Organization in Turkey, offering efficient solutions for drug development with a team of over 350 employees | Research Services | 🇹🇷 Istanbul | 472 | 2008 |
| 25 | [TÜMAŞ TÜRK MÜHENDİSLİK, MÜŞAVİRLİK VE MÜTEAHHİTLİK A.Ş.](https://www.tamtam.ai/c/tumas-turk-muhendislik-musavirlik-ve-muteahhitlik-a-s) (tumas.com.tr)<br>Providing pre-project planning, design, engineering, consultancy, and construction services for all project stages, including tendering, supervision, and post-implementation services | Design Services | 🇹🇷 Çankaya | 471 | 1969 |
| 26 | [Eksen](https://www.tamtam.ai/c/eksen) (eksen.eu)<br>Independent market research agency offering qualitative and quantitative fieldwork in emerging markets, specialized in various sectors with ISO 20252:2012 certification | Market Research | 🇹🇷 Istanbul | 426 | 2004 |
| 27 | [OKUL YAPI](https://www.tamtam.ai/c/okul-yapi) (okulyapi.com)<br>Innovative and effective educational spaces designed by OKULYAPI for future generations, providing turnkey projects and various classroom concepts in Turkey | Architecture and Planning | 🇹🇷 Istanbul | 422 | 2008 |
| 28 | [BDO Türkiye](https://www.tamtam.ai/c/bdo-turkiye) (bdo.com.tr)<br>An audit and consultancy organization providing professional services in Audit & Assurance, Tax, Social Security, Accounting, and Advisory across the globe | Accounting | 🇹🇷 Istanbul | 414 | 1981 |
| 29 | [DefineX](https://www.tamtam.ai/c/definex) (teamdefinex.com)<br>A forward-thinking consulting house and venture builder focused on digital acceleration, innovation, and cultivating talent for the success of tomorrow | Business Consulting and Services | 🇹🇷 Istanbul | 405 | 2019 |
| 30 | [NKY Architects and Engineers](https://www.tamtam.ai/c/nky-architects-and-engineers) (nky.com.tr)<br>Specialized in project management and design for hospitals and educational facilities, providing professional services worldwide with a focus on quality development | Architecture and Planning | 🇹🇷 Çankaya | 405 | 1975 |
| 31 | [SIGMA](https://www.tamtam.ai/c/sigma) (sigmamuhendislik.com.tr)<br>With over 30 years of experience, we are a trusted partner in engineering and consulting services for leading organizations in Turkey | Construction | 🇹🇷 Beşiktaş | 394 |  |
| 32 | [KoçZer](https://www.tamtam.ai/c/koczer) (koczer.com)<br>Leader in procurement & supply chain management with 20+ years of experience, providing end-to-end solutions, strategic roadmaps, mass purchases, and technological solutions | Business Consulting and Services | 🇹🇷 Istanbul | 390 | 2003 |
| 33 | [Mayen Telekomünikasyon Hizmetleri A.Ş.](https://www.tamtam.ai/c/mayen-telekomunikasyon-hizmetleri-a-s) (mayen.com)<br>Mayen offers innovative outsourcing solutions in various sectors, including customer services, RPA, digital training, social media monitoring, HR, payroll, and testing services | Outsourcing and Offshoring Consulting | 🇹🇷 Şişli | 380 | 2004 |
| 34 | [UBM ULUSLARARASI BIRLESMIS MUSAVIRLER MUSAVIRLIK HIZMETLERI A.Ş](https://www.tamtam.ai/c/ubm-uluslararasi-birlesmis-musavirler-musavirlik-hizmetleri-a-s) (ubm.com.tr)<br>A leading technical consultancy specializing in environmental, infrastructure, and transportation projects, with expertise in financial analysis and project management | Civil Engineering | 🇹🇷 Çankaya | 377 | 1950 |
| 35 | [Prokon Mühendislik ve Müşavirlik A.Ş.](https://www.tamtam.ai/c/prokon-muhendislik-ve-musavirlik-a-s) (prokon.com.tr)<br>Specializing in design, engineering, and consultancy services for a wide range of industrial projects worldwide with a focus on quality and innovation | Civil Engineering | 🇹🇷 Kahramankazan | 370 | 1974 |
| 36 | [Sistem Global Danışmanlık A.Ş.](https://www.tamtam.ai/c/sistem-global-dan-smanl-k-a-s) (sistemglobal.com.tr)<br>Provider of financial, legal, and consultancy services for technology companies, specializing in corporate finance, tax, audit, patents, and international funds | Business Consulting and Services | 🇹🇷 Istanbul | 368 | 1996 |
| 37 | [Kendi Agency](https://www.tamtam.ai/c/kendi-agency) (kendi.agency)<br>An independent advertising agency that values authenticity, creating a space where employees and clients can express their true selves | Advertising Services | 🇹🇷 Kagithane | 366 | 2007 |
| 38 | [Subaşı Gümrük Müşavirliği A.Ş.](https://www.tamtam.ai/c/subas-gumruk-musavirligi-a-s) (subasi.net)<br>Established in 1948 as a Customs Brokering entity, employing a skilled team of 470 individuals including 27 customs advisors Specializing in customs clearance services and ensuring accurate, efficient processing through detailed analysis of goods and compliance with relevant regulations | Transportation, Logistics, Supply Chain and Storage | 🇹🇷 Istanbul | 364 | 1948 |
| 39 | [Autoban](https://www.tamtam.ai/c/autoban) (autoban.com)<br>Internationally renowned studio specializing in architecture, interiors, product design, and experiential design with a focus on storytelling, craftsmanship, and sensory experiences | Architecture and Planning | 🇹🇷 Istanbul | 360 | 2003 |
| 40 | [SUR MALİ MÜŞAVİRLİK](https://www.tamtam.ai/c/sur-mali-musavirlik)<br>Providing accounting and financial consultancy services for individuals and businesses, including bookkeeping, financial statements, tax filings, and advisory services | Accounting | 🇹🇷 Istanbul | 355 | 2009 |
| 41 | [MEDEX SMO](https://www.tamtam.ai/c/medex-smo) (medex-smo.com)<br>Specializing in managing clinical research sites, providing site management services to improve trial enrollment, compliance, and performance for pharmaceutical and biotechnology companies | Medical Practices | 🇹🇷 Istanbul | 349 | 2013 |
| 42 | [E Mali Müşavirlik](https://www.tamtam.ai/c/e-mali-musavirlik) (emusavirlik.com)<br>Specializing in advisory services in Mali, providing expert guidance and consulting solutions to clients | Financial Services | 🇹🇷 Istanbul | 345 | 2015 |
| 43 | [People](https://www.tamtam.ai/c/people-besiktas) (peoplecomms.com.tr)<br>A leading media agency in Turkey with a highly skilled team offering integrated communication plans including media planning, buying, strategies, research, and modeling | Advertising Services | 🇹🇷 Beşiktaş | 341 |  |
| 44 | [Grant Thornton Türkiye](https://www.tamtam.ai/c/grant-thornton-turkiye) (grantthornton.com.tr)<br>An international organization with about 250 professionals in Istanbul, Ankara, and Bursa, providing independent audit, tax, accounting, and advisory services since 1986 | Accounting | 🇹🇷 Maslak | 336 | 1986 |
| 45 | [Forvis Mazars Türkiye](https://www.tamtam.ai/c/forvis-mazars-turkiye) (forvismazars.com)<br>Global professional services firm serving over 1,500 companies worldwide with a team of 350+ professionals across multiple offices, committed to highest standards and ethics | Accounting | 🇹🇷 Istanbul | 334 | 1977 |
| 46 | [FEV Türkiye](https://www.tamtam.ai/c/fev-turkiye) (fev.com)<br>A provider of turnkey engineering solutions in the automotive industry, specializing in vehicle development, software, autonomous driving, and propulsion systems | Motor Vehicle Manufacturing | 🇹🇷 Istanbul | 330 | 2011 |
| 47 | [Solvia Digital Solutions](https://www.tamtam.ai/c/solvia-digital-solutions) (solviads.com)<br>Design, integrate, and optimize SAP and IT solutions to enhance agility, resilience, and long-term digital transformation for businesses. | IT Services and IT Consulting | 🇹🇷 Istanbul | 318 | 2014 |
| 48 | [Uniarch Klinik Mühendislik ve Klinik Alan Tasarım A.Ş](https://www.tamtam.ai/c/uniarch-klinik-muhendislik-ve-klinik-alan-tasar-m-a-s) (uniarch.com.tr)<br>Uniarch aims to provide secure and efficient healthcare services by offering consultancy, planning, and project services for the design, technology selection, and operations of healthcare facilities | Hospitals | 🇹🇷 Kartal | 317 |  |
| 49 | [SPA MÜHENDİSLİK](https://www.tamtam.ai/c/spa-muhendislik) (spalinetr.com)<br>Specializing in terminal operation systems in the fuel and chemical industry, designing fire systems, and providing risk analysis solutions for process safety | Engineering Services | 🇹🇷 Ankara | 316 |  |
| 50 | [DETAM Sirketler Grubu](https://www.tamtam.ai/c/detam-sirketler-grubu) (detam.com.tr)<br>A leading consultancy group in Turkey providing a wide range of services in occupational health, safety, environmental services, legal consulting, and HR | Business Consulting and Services | 🇹🇷 Ankara | 284 | 1996 |

## How this list is built

Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 12, 2026.

## More company lists in Turkey

- [The largest companies in Turkey](https://www.tamtam.ai/l/largest-companies-turkey) (3,556)
- [Multinational companies in Turkey](https://www.tamtam.ai/l/multinational-companies-turkey) (790)
- [Manufacturers in Turkey](https://www.tamtam.ai/l/manufacturers-turkey) (762)
- [Companies with in-house R&D in Turkey](https://www.tamtam.ai/l/r-and-d-companies-turkey) (512)
- [Retail chains in Turkey](https://www.tamtam.ai/l/retail-chains-turkey) (376)
- [Companies with a mobile app in Turkey](https://www.tamtam.ai/l/companies-with-mobile-app-turkey) (312)
- [Corporate groups and holding companies in Turkey](https://www.tamtam.ai/l/holding-companies-turkey) (304)
- [Critical infrastructure operators in Turkey](https://www.tamtam.ai/l/critical-infrastructure-operators-turkey) (282)
- [Public sector organisations in Turkey](https://www.tamtam.ai/l/public-sector-organisations-turkey) (227)
- [Hardware manufacturers in Turkey](https://www.tamtam.ai/l/hardware-companies-turkey) (224)
- [Energy companies in Turkey](https://www.tamtam.ai/l/energy-companies-turkey) (197)
- [Food and beverage companies in Turkey](https://www.tamtam.ai/l/food-and-beverage-companies-turkey) (197)
- [Consumer goods companies in Turkey](https://www.tamtam.ai/l/consumer-goods-companies-turkey) (193)
- [Food and Beverage Manufacturing companies in Turkey](https://www.tamtam.ai/l/food-and-beverage-manufacturing-companies-turkey) (184)
- [Hotel and hospitality groups in Turkey](https://www.tamtam.ai/l/hospitality-groups-turkey) (176)
- [E-commerce companies in Turkey](https://www.tamtam.ai/l/ecommerce-companies-turkey) (172)
- [Higher Education companies in Turkey](https://www.tamtam.ai/l/higher-education-companies-turkey) (158)
- [Food and Beverage Services companies in Turkey](https://www.tamtam.ai/l/food-and-beverage-services-companies-turkey) (149)
- [Family-owned companies in Turkey](https://www.tamtam.ai/l/family-owned-companies-turkey) (137)
- [Financial services firms in Turkey](https://www.tamtam.ai/l/financial-services-firms-turkey) (134)
- [Motor Vehicle Manufacturing companies in Turkey](https://www.tamtam.ai/l/motor-vehicle-manufacturing-companies-turkey) (134)
- [Publicly traded companies in Turkey](https://www.tamtam.ai/l/publicly-traded-companies-turkey) (131)
- [Construction companies in Turkey](https://www.tamtam.ai/l/construction-companies-turkey) (129)
- [Automotive manufacturers and suppliers in Turkey](https://www.tamtam.ai/l/automotive-companies-turkey) (128)

## The same list elsewhere in Turkey

- [Professional services firms in Istanbul](https://www.tamtam.ai/l/professional-services-firms-istanbul) (41)

## The same list elsewhere

- [Professional services firms in the world](https://www.tamtam.ai/l/professional-services-firms-in-the-world) (24,737)
- [Professional services firms in the Middle East](https://www.tamtam.ai/l/professional-services-firms-in-the-middle-east) (253)

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Source: https://www.tamtam.ai/l/professional-services-firms-turkey