Montreal's professional services sector features a mix of large established firms and mid-sized companies, predominantly in engineering, IT consulting, and broader professional services. Notable firms include SNC-Lavalin, a global engineering and nuclear organization; WSP in Canada, which provides engineering, advisory, and science expertise; and Logica, a global provider of IT and business process services. Raymond Chabot Grant Thornton offers accounting and consulting, while Alithya specializes in digital technology services.
A clear pattern among these companies is their strong representation in engineering services, with firms like BPA, Artelia Canada, and gbi contributing to this cluster. Additionally, IT consulting and business consulting are well-represented, indicating a robust demand for specialized technical and strategic advice in the region. Most of these larger firms are headquartered in Montreal, serving both local and international clients.
| # | 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 |
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 | |||
| 5 |
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 | |||
| 6 | 1,269 | ||||
| 7 |
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 | |||
| 8 |
AVENIR GLOBALavenir.global
A global holding and management group with specialized communication agencies in Canada, the US, Europe, and the Middle East |
1,020 | |||
| 9 |
Richterrichter.ca
Business | Family Office providing strategic advice on business and family matters, guiding successful entrepreneurs to shape their legacy across generations |
922 | |||
| 10 |
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 | |||
| 11 | 761 | ||||
| 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 | 597 | ||||
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| 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 |
FBL S.E.N.C.R.L. Société de comptables professionnels agréésfbl.com
A top accounting firm in Quebec with over 40 years of experience offering services in accounting, taxation, business valuation, financing, and international assistance |
488 | |||
| 19 |
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 | |||
| 20 |
Indero (formerly Innovaderm)inderocro.com
A specialized CRO in dermatology, providing expert guidance and services for Phase 1 to Phase IV studies worldwide since 2000 |
480 | |||
| 21 |
AAA Canadaaaa-canada.ca
Providing subcontracting, technical assistance, and productivity solutions in Aerospace, Ground Transportation, and Defense sectors worldwide through international expertise |
440 | |||
| 22 |
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 | |||
| 23 |
Legerleger360.com
A leading Canadian market research and analytics company with over 600 employees across 8 offices, serving prestigious clients since 1986 |
428 | |||
| 24 |
Beyond Technologiesbeyondtechnologies.com
Professional services specializing in SAP integration and business process optimization, leveraging extensive industry expertise to deliver practical, innovative solutions. |
414 | |||
| 25 | 403 | ||||
| 26 |
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 | |||
| 27 |
Sid Leesidlee.com
Multidisciplinary creative community specializing in brand building, expression, and experience through design, advertising, architecture, and interactive communication. |
398 | |||
| 28 |
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 | |||
| 29 |
Langlois Avocatslanglois.ca
Leading independent law firm in Quebec with over 175 lawyers offering high-quality legal services in various areas such as construction, energy, life sciences, and more |
382 | |||
| 30 |
Quantum Management Services Ltd.quantum.ca
A recruitment agency with 55 years of experience, connecting organizations and individuals for permanent, contract, and temporary positions across various industries |
362 | |||
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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
- Professional services firms in Canada 481
- Professional services firms in Ontario 211
- Professional services firms in the province of Quebec 103
- Professional services firms in Alberta 81
- Professional services firms in British Columbia 59
- Professional services firms in Toronto 117
- Professional services firms in Calgary 55
- Professional services firms in Vancouver 34