The companies listed in Ottawa are predominantly public sector entities and essential service providers. They include large government administrations, healthcare institutions, and critical infrastructure operators. Notable examples are Canada Post / Postes Canada, a nationwide postal service; the Canadian Armed Forces, providing defense and security; The Ottawa Hospital, a teaching and research hospital; and Shared Services Canada, modernizing government IT infrastructure.
A significant pattern among these organizations is their role in maintaining public welfare and national operations. Many are federal agencies or government-related entities, such as Canada Border Services Agency and Canadian Coast Guard/Garde côtière canadienne, both focused on national security and maritime services. This concentration reflects Ottawa's status as the capital city.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
Canada Post / Postes Canadacanadapost-postescanada.ca
Nationwide postal service with extensive retail network, delivering parcels and mail to over 17 million Canadian addresses. |
23,941 | |||
| 2 |
Canadian Armed Forces | Forces armées canadiennesforces.ca
Offering over 100 trades, the organization provides world-class qualifications, competitive salaries, benefits, stability, and exciting opportunities for travel, adventure, and making a difference |
20,412 | |||
| 3 |
City of Ottawa / Ville d’Ottawajobs-emplois.ottawa.ca
A diverse workforce providing essential programs and services for over one million residents in Ottawa, with a focus on customer service and community well-being |
9,194 | |||
| 4 |
The Ottawa Hospitalottawahospital.on.ca
Innovative teaching and research hospital providing specialized care, developing new treatments, and improving patient care through community engagement and global impact |
7,679 | |||
| 5 |
Shared Services Canada | Services partagés Canadacanada.ca
Modernizing Government of Canada's IT infrastructure by delivering email, data centre, telecommunication, videoconferencing, and Wi-Fi services to customers |
5,161 | |||
| 6 |
Canada Border Services Agency | Agence des services frontaliers du Canadacbsa-asfc.gc.ca
Ensures national security and economic prosperity by managing and monitoring international travel and trade at Canada's borders. |
4,369 | |||
| 7 |
Canadian Blood Servicesblood.ca
Canada's national organization responsible for ensuring a secure and sustainable supply of blood and organs for transfusion and transplantation |
3,745 | |||
| 8 |
NAV CANADAnavcanada.ca
Operates Canada's civil air navigation service, ensures safe and efficient aircraft movement, provides air traffic control, weather briefings, and navigation aids |
3,416 | |||
| 9 |
Canadian Coast Guard/Garde côtière canadiennecanada.ca
A federal agency that operates a civilian fleet and provides maritime services to Canadians, ensuring safe waters, environmental protection, and economic growth |
2,892 | |||
| 10 |
CHEOcheo.on.ca
A global leader in pediatric health care and research, providing excellence in complex care, education, and community partnership for children and youth |
2,784 | |||
| 11 |
Bank of Canadabankofcanada.ca
Central bank focused on maintaining low, stable inflation and promoting economic and financial welfare for Canada's overall economic health. |
2,496 | |||
| 12 |
VON Canadavon.ca
A nonprofit organization providing innovative clinical, personal, and social support services for people to live comfortably in their own homes |
1,879 | |||
| 13 |
Queensway Carleton Hospitalqch.on.ca
A patient and family-centered hospital in Ottawa providing acute care services with a focus on emergency, childbirth, geriatrics, mental health, and rehabilitation |
1,335 | |||
| 14 |
Bruyère Healthbruyere.org
The company provides a range of health care services including rehabilitation, complex care, family health teams, long-term care, and senior living options Their mission is to enhance quality of life through integrated care |
1,298 | |||
| 15 |
CATSA / ACSTAcatsa-acsta.gc.ca
A government corporation in Canada responsible for air transportation security, including screening passengers, baggage, and airport workers at major airports nationwide |
1,184 | |||
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 |
University of Ottawa Heart Instituteottawaheart.ca
A leading cardiovascular health center in Canada providing high-tech, personalized care, advancing cardiac medicine through research, and pioneering new treatments globally |
1,087 | |||
| 17 |
Hôpital Montforthopitalmontfort.com
An academic hospital in Ontario, focused on exceptional patient care and staff well-being, emphasizing collaboration, innovation, and skill development |
1,054 | |||
| 18 |
The Royaltheroyal.ca
specialized mental health care, advocacy, research, education, and fundraising to support recovery for complex and treatment-resistant mental illness |
962 | |||
| 19 |
Ottawa Police Serviceottawapolice.ca
A dedicated police service in Ottawa providing excellent service since 1995 Connect with us online for career opportunities and recruitment information |
834 | |||
| 20 |
Canadian Northcanadiannorth.com
A transportation service provider connecting people and communities in Inuit Nunangat and NWT through cargo, charter, and scheduled flights |
827 | |||
| 21 |
Alterna Savingsalterna.ca
A leading financial institution with over 115 years of experience, offering a wide range of services to over 200,000 members across Ontario |
656 | |||
| 22 |
OC Transpooctranspo.com
Public transportation provider in Canada's national capital with a fleet of accessible buses and trains, focused on sustainability and expanding light rail system |
553 | |||
| 23 |
Carefor Health & Community Servicescarefor.ca
Providing home health care and community support services since 1897, supporting seniors and people with disabilities to live with choice and dignity in Eastern Ontario |
464 | |||
| 24 |
Payments Canadapayments.ca
Facilitating billions of dollars in daily transactions, this organization supports Canada's economy through essential clearing and settlement infrastructure for payments |
435 | |||
| 25 |
Ottawa Public Health - Santé publique Ottawaottawapublichealth.ca
A public health organization in Ottawa working with community partners to improve residents' health and safety through programs, services, and public policies |
400 | |||
| 26 |
EORLA - Eastern Ontario Regional Laboratory Associationeorla.ca
A non-profit organization operating 19 hospital-based clinical laboratories in Eastern Ontario, providing high-quality, patient-focused diagnostic testing services to the region |
364 | |||
| 27 |
Home and Community Care Support Services Champlainhealthcareathome.ca
Providing exceptional care to individuals in their homes, with a commitment to quality and compassion |
263 | |||
| 28 |
First Aircanadiannorth.com
A leading airline in Canada's Arctic, providing scheduled passenger and cargo services to over 30 northern communities with a fleet of 17 aircraft |
236 | |||
| 29 |
Telesattelesat.com
Provides satellite communication services, headquartered in Ottawa with offices in the United States and Brazil, acquired by Loral Space & Communications and Public Pension Investment Board. |
201 | |||
| 30 |
Energy Ottawaenergyottawa.com
Innovative energy company in Ontario producing green power through hydroelectric, solar, and landfill gas-to-energy facilities, along with energy management and infrastructure services |
11 | |||
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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 11, 2026.
More company lists in Ottawa
- The largest companies in Ottawa 350
- Public sector organisations in Ottawa 49
- Multinational companies in Ottawa 42
- Education providers in Ottawa 30
- Government Administration companies in Ottawa 30
The same list elsewhere in Canada
- Critical infrastructure operators in Canada 767
- Critical infrastructure operators in Ontario 344
- Critical infrastructure operators in the province of Quebec 126
- Critical infrastructure operators in Alberta 124
- Critical infrastructure operators in British Columbia 78
- Critical infrastructure operators in Manitoba 27
- Critical infrastructure operators in Toronto 120
- Critical infrastructure operators in Calgary 83
- Critical infrastructure operators in Montreal 51
- Critical infrastructure operators in Vancouver 26
- Critical infrastructure operators in Mississauga 24