| Altair Engineering Canada | Information Technologies (IT) | altair.com |
| Altamed Pharma | Life Sciences and Health Technologies (LSHT) | altamed.ca |
| Altapex Construction | Building Contractors | altapex.com |
| Altar Creative Services Inc | Shopping Mall | facebook.com |
| Altasciences (Algorithme Pharma Inc.) | Life Sciences and Health Technologies (LSHT) | algopharm.com |
| Altaï Canada | Tout Tourisme et hôtels | canada.altaibasecamp.com |
| Alten Canada Inc | Information Technologies (IT) | alten.ca |
| Alter ABC Inc | Health Services | alter-abc.com |
| Alter-Thérapie | Alternative Health | altertherapie.com |
| Alternateur Et Demarreur Moto VTT Plus | Alternators & Starters | — |
| Alternative Chiropratique | Chiropractors | — |
| Alternative SM (paysagiste) | Landscaping | — |
| Alternatives | Tout Enseignement et savoir, Tout Médias montréalais | alternatives.ca |
| Alternatives International | International Organizations | alternatives.ca |
| Alternator Starter | Alternators & Starters | — |
| Altitude | Roofing | — |
| ALTITUDE AEROSPACE | Aerospace | altitudeaero.com |
| Altitude Aerospace Inc | Aircraft Maintenance, Service & Storage | altitudeaero.com |
| Altitude Aerospace Inc | Aircraft Maintenance, Service & Storage | — |
| Altium | Architectural & Construction Specifications | — |
| Alto Design | Clean Technologies, Tout Entreprises et services | alto-design.com |
| Alto Shaam Canada | Commercial Kitchen Equipment | alto-shaam.ca |
| Altopro Infographie Inc | Computer Graphics Design & Animation | — |
| Altra Foods Inc | Bakery Supplies | altrafoods.com |
| ALUBOX (DIVISION DE JE LORTIE COMPAGNIE LTÉE) | Aerospace | alubox.ca |
| Alumalco | Home Improvement | alumalco.ca |
| Alumcomplete Production de Portes Coulissantes Inc | Closet Organizers & Accessories | alumcomplete.ca |
| Alumi-Depot (9076-6627 Qc Inc) | Balconies | — |
| Alumicor Limited | Aluminum, Aluminum Products, Architects | alumicor.com |
| Alumilex | Aluminum | alumilex.com |
| Alumilex Inc. | Tout Entreprises et services | alumilex.com |
| Aluminium Austria Metall Quebec Inc | Aluminum | — |
| Aluminium Distinction | Aluminum, Aluminum Fabricators | — |
| Aluminium Fenebel 1964 Inc | Aluminum, Aluminum Products | fenebel.com |
| Aluminium J P M Inc | Building Contractors | facebook.com |
| Aluminium La Rénovation | Home Improvement | aluminiumlr.ca |
| Aluminium Lmg | Awning & Canopy Sales & Service | aluminiumlmg.com |
| Aluminium Maurice Forest Inc | Aluminum, Aluminum Products, Balconies | aluminiumforest.com |
| Aluminium Orlando | Aluminum | facebook.com |
| Alumould & Tool Ltd | Aluminum | — |
| Aluron Biopharma | Life Sciences and Health Technologies (LSHT) | aluronbiopharma.com |
| Alvéole | Beekeeping Supplies, Tout Arts et divertissement, Tout Communautés et société | alveole.buzz |
| Alyn Simard | Audiologists | — |
| Alyn Simard | Audiologists | — |
| Alyn Simard Audioprothésiste | Audiologists | alynsimardaudio.com |
| Am Services | Cleaning Services, Cleaning Service | am-services.ca |
| AM Services | Cleaning Services, Cleaning Service | — |
| Am-Can Chemical Inc | Chemicals | facebook.com |
| Amani Hair Studio Montreal | Beauty & Fitness, Hairdressers & Beauty Salons | amanihairstudio.com |
| Amaranthe Jardins | Landscaping | yelp.ca |
