| Name | Industry | Sector | Headquarters | Founded | Notes | Status |
| 1-800-GOT-JUNK? | Industrials | Waste & disposal services | Vancouver | 1989 | Junk removal | P | A |
| Norda Stelo | Industrials | Construction & Materials | Quebec City | 1963 | Integrated projects | P | A |
| 3Way International Logistics | Industrials | Business support services | Mississauga | 2001 | Freight forwarding | P | A |
| A Buck or Two | Consumer services | Specialty retailers | Vaughan | 1988 | Retail | P | A |
| A&W | Consumer services | Restaurants & bars | North Vancouver | 1956 | Fast food chain | P | A |
| ABS Friction | Manufacturing | Brake pads | Guelph, Ontario | 1995 | Vehicle aftermarket | P | A |
| Access Communications | Telecommunications | Fixed line telecommunications | Regina | 1974 | Cable television provider | P | A |
| Ache Records | Consumer services | Broadcasting & entertainment | Vancouver | 1999 | Record label | P | A |
| Addition Elle | Consumer services | Apparel retailers | Montreal | 1967 | Women's clothing retailer | P | A |
| Advanced Cyclotron Systems | Health care | Medical equipment | Richmond | 2003 | Medical cyclotrons | P | A |
| Affinity Credit Union | Financials | Banks | Saskatoon | 2005 | Credit union | P | A |
| AHED | Consumer goods | Recreational products | Toronto | 1969 | Guitar equipment, defunct | P | D |
| Air Canada | Consumer services | Airlines | Montreal | 1937 | Flag carrier, largest airline of Canada | P | A |
| Air Miles | Consumer services | Travel & tourism | Toronto | 1992 | Loyalty programs | P | A |
| Aldo Group | Consumer services | Apparel retailers | Montreal | 1972 | Footwear retailer | P | A |
| AldrichPears Associates | Industrials | Business support services | Vancouver | 1979 | Exhibit design | P | A |
| Algonquin Power & Utilities | Utilities | Alternative electricity | Oakville | 1997 | Renewable energy | P | A |
| Allied Shipbuilders | Industrials | Commercial vehicles & trucks | North Vancouver | 1948 | Shipyard | P | A |
| Alta Newspaper Group | Consumer services | Publishing | Vancouver | 1999 | Media holding | P | A |
| Alterra Power | Utilities | Alternative electricity | Vancouver | 2011 | Renewable energy | P | A |
| Angoss | Technology | Software | Toronto | 1984 | Analytic software | P | A |
| Apotex | Health care | Pharmaceuticals | Toronto | 1974 | Generic pharmaceuticals | P | A |
| Appnovation | Technology | Software | Vancouver | 2007 | Software developer | P | A |
| Arc'teryx | Consumer services | Apparel retailers | North Vancouver | 1989 | Outdoor apparel/equipment | P | A |
| Areva Resources Canada | Basic materials | General mining | Saskatoon | 1964 | Uranium | P | A |
| Aritzia | Consumer goods | Clothing & accessories | Vancouver | 1984 | Clothing | P | A |
| Army & Navy Stores | Consumer services | Broadline retailer | Vancouver | 1919 | Discount department stores, defunct 2020 | P | D |
| Arsenal Pulp Press | Consumer services | Publishing | Vancouver | 1971 | Book publisher | P | A |
| ATB Financial | Financials | Asset management | Edmonton | 1938 | State financial services | S | A |
| ATI Technologies | Technology | Semiconductors | Markham | 1985 | Semiconductors, defunct 2006 | P | D |
| AtkinsRéalis | Industrials | Diversified industrials | Montreal | 1911 | Engineering, construction | P | A |
| Atmosphere Visual Effects | Consumer services | Broadcasting & entertainment | Vancouver | 2003 | Movie special effects | P | A |
| Atwill-Morin | Basic materials | Construction & Materials | Montreal | 2007 | Masonry restoration, heritage preservation | P | A |
| Ballard Power Systems | Industrials | Electrical components & equipment | Burnaby | 1979 | Fuel cells | P | A |
| Banff Lodging Co | Consumer services | Hotels | Banff | 1985 | Lodges | P | A |
| Bank of Montreal | Financials | Banks | Montreal | 1817 | Bank | P | A |
| Bard Ventures | Basic materials | General mining | Vancouver | 1981 | Molybdenum mining | P | A |
| Barrick Gold | Basic materials | Gold mining | Toronto | 1983 | Gold extraction | P | A |
| Bausch Health | Health care | Pharmaceuticals | Laval | 1960 | Specialty pharmaceuticals | P | A |
| BBC Kids | Consumer services | Broadcasting & entertainment | Burnaby | 2001 | Children's television | P | A |
| BC Hydro | Utilities | Alternative electricity | Vancouver | 1961 | Hydro-electric | S | A |
| BC Research | Industrials | Business support services | Vancouver | 1944 | Research, defunct 2007 | P | D |
| Becker's | Consumer services | Specialty retailers | Toronto | 1957 | Retail chains | P | A |
| Bell Canada | Telecommunications | Fixed line telecommunications | Montreal | 1880 | Telecom, part of BCE Inc | P | A |
| Bell MTS | Telecommunications | Fixed line telecommunications | Winnipeg | 1905 | Telecom, part of BCE Inc | P | A |
| Ben Moss Jewellers | Consumer services | Specialty retailers | Winnipeg | 1910 | Jewelry retailer | P | A |
| Bennett Environmental | Industrials | Waste & disposal services | Oakville | 1991 | Defunct 2013 | P | D |
| Big Blue Bubble | Technology | Software | London | 2004 | Software firm, mobile games | P | A |
| BigPark | Technology | Software | Vancouver | 2007 | Software firm, part of Microsoft (US) | P | D |