This selection of large consulting firms in Montreal focuses on professional services, IT consulting, and engineering. Among them are SNC-Lavalin, a global engineering services and nuclear organization, and WSP in Canada, a professional services firm with expertise in engineering, advisory, and science. BDC supports entrepreneurs through financing and consulting, while Raymond Chabot Grant Thornton offers assurance, taxation, and consulting services. Alithya provides digital technology services, and BPA specializes in mechanical, electrical, and structural engineering.
A notable pattern among these companies is their significant employee count, indicating a concentration of large-scale operations within Montreal's consulting sector. All the companies listed have their headquarters in Montreal, highlighting the city as a central hub for these professional and engineering services.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
SNC-Lavalinatkinsrealis.com
Global engineering services and nuclear organization connecting people, data, and technology to transform infrastructure and energy systems worldwide. |
11,913 | |||
| 2 |
WSP in Canadawsp.com
professional services firm unites engineering, advisory, science expertise; shapes communities; advances humanity; delivers projects across sectors globally. |
10,459 | |||
| 3 | 6,113 | ||||
| 4 | 4,739 | ||||
| 5 |
Raymond Chabot Grant Thorntonrcgt.com
A leading accounting firm with over 2,300 professionals offering assurance, taxation, consulting, and business recovery services in Quebec and globally |
2,426 | |||
| 6 |
Alithyaalithya.com
A global digital technology services company providing practical IT solutions tailored to complex business challenges, with a focus on strategy and digital transformation |
2,418 | |||
| 7 | 1,269 | ||||
| 8 |
COFOMOcofomo.com
Canadian IT and business consulting leader specializing in digital transformation with a team of 3,000 professionals offering innovative solutions nationwide |
1,201 | |||
| 9 |
AVENIR GLOBALavenir.global
A global holding and management group with specialized communication agencies in Canada, the US, Europe, and the Middle East |
1,020 | |||
| 10 |
Richterrichter.ca
Business | Family Office providing strategic advice on business and family matters, guiding successful entrepreneurs to shape their legacy across generations |
922 | |||
| 11 |
Stantec au Québecstantec.com
Global leader in engineering and sustainable development, with expertise in various sectors, providing services from concept to completion with innovation and client needs in mind |
801 | |||
| 12 |
SNC-Lavalin Rail & Transit (formerly Interfleet)snclavalin.com
Global engineering and construction group providing industry-leading services in infrastructure, oil and gas, mining, power, and rail and transit systems |
659 | |||
| 13 |
Artelia Canadaarteliagroup.ca
Multidisciplinary engineering firm providing innovative solutions in mobility, energy, environment, water, industry, and telecom across Canada with global expertise. |
642 | |||
| 14 | 614 | ||||
| 15 |
Optimum Financial Groupoptimumfinancier.com
Financial group providing services in actuarial consulting, asset management, insurance, IT, and real estate Operating globally with over 600 employees and significant assets under management |
559 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 16 |
LAPORTElaporteconsultants.com
Specialized engineering firm providing process, building, and utility design solutions to Pharmaceutical, Agrifood, and Bioindustrial industries globally with long-term client relationships |
543 | |||
| 17 |
Groupe ABSgroupeabs.com
Established in 1993, Groupe ABS offers a wide range of services in material engineering, geotechnics, environmental science, and specialized divisions in drilling and contaminated soil treatment |
492 | |||
| 18 |
Tetra Tech au Québectetratech.com
A global leader in consulting, engineering, and technical services with expertise in various sectors, providing innovative solutions for projects worldwide |
485 | |||
| 19 |
GCM Consultantsgcmconsultants.com
The company delivers high-performance engineering services for various industrial sectors, offering studies, engineering, project management, and construction services for projects up to $200M |
432 | |||
| 20 |
Beyond Technologiesbeyondtechnologies.com
Professional services specializing in SAP integration and business process optimization, leveraging extensive industry expertise to deliver practical, innovative solutions. |
414 | |||
| 21 |
Normandin Beaudrynormandin-beaudry.ca
Established in 1992, this consulting firm in Montreal, Toronto, and Quebec City specializes in human capital and financial performance through advisory services in eight areas of expertise |
401 | |||
| 22 |
MSP Corpmspcorp.ca
This company acquires and empowers high-performing Managed Service Providers in North America, providing resources, technology, and business support to enhance their services |
398 | |||
| 23 |
Mecanicamecanicasolutions.com
Global provider of engineering services for aerospace, automotive, and AEC industries Specializing in PLM/CAD/CAM solutions, onsite support, R&D, engineering services, and custom software development for clients |
393 | |||
| 24 |
Therrien Couture Joli-Coeurgroupetcj.ca
A multidisciplinary team supports clients and partners with a collaborative, innovative, and value-creating approach, focusing on commitment, audacity, simplicity, and relevance |
338 | |||
| 25 | 319 | ||||
| 26 |
ALTEN Canadaalten.ca
Global consulting firm specializing in Engineering and IT, with over 30 years experience Providing specialized professionals, tailored solutions, and employee-focused support |
318 | |||
| 27 |
Tetra Tech Industriestetratech.com
A global provider of advanced engineering services for heavy industries, specializing in plant engineering, investment program management, and construction projects |
255 | |||
| 28 |
Victrixvictrix.ca
A leading IT services company in Quebec, specializing in implementing enterprise productivity solutions to enhance performance and competitiveness through specialized technology services |
240 | |||
| 29 | 233 | ||||
| 30 |
LIDD Supply Chain Consultantslidd.com
Global consulting firm specializing in supply chain strategy, technology, and infrastructure for consumer products, food & beverage, retail, e-commerce, and distribution industries |
182 | |||
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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.
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The same list elsewhere in Canada
- Consulting firms in Canada 345
- Consulting firms in Ontario 141
- Consulting firms in the province of Quebec 88
- Consulting firms in Alberta 54
- Consulting firms in British Columbia 45
- Consulting firms in Toronto 70
- Consulting firms in Calgary 36
- Consulting firms in Vancouver 28