| ALTA Consulting | |
| ALTA Electronics, Inc. | Ontario |
| AltaCom | |
| Altair Electronics | Ontario |
| AltaLink | |
| Altasciences | |
| Altaso Ltd | Alberta |
| AltaStream Control Systems | British Columbia |
| altavia.cloudraker | Quebec |
| Altavision Geographics | Saskatchewan |
| Altea Communications | Quebec |
| Altecon Data Communications, Inc. | Ontario |
| Alten Canada | Quebec |
| Alten Canada | |
| Alteo, Inc. | Quebec |
| AlterAction | Quebec |
| alterBiota | |
| Alterna | |
| Alterna Bank | Ontario |
| Alterna Savings | |
| AlternaTel, Inc. | Ontario |
| AlternativeBroadband.com | Ontario |
| Alternet Internet | British Columbia |
| Alterum | |
| Altilogix | Quebec |
| AltimaTelecom | Quebec |
| Altimum IMS | Quebec |
| Altinformatique | Quebec |
| Altis MSP | Alberta |
| Altitude Accelerator | |
| Altitude Aerospace | |
| ALTITUDE Centre de L'Aviation, Inc. | Quebec |
| Altitude Communications | Alberta |
| Altitude Information Systems | British Columbia |
| Altitude Logic | |
| Altius Renewable Royalties | |
| AltNexus, Inc. | Ontario |
| Altruistic Informatics Consulting, Inc. | Ontario |
| AltumView | |
| Altus Group Ltd | Ontario |
| Alyson Software | Ontario |
| Alytx | |
| AM Canada, Inc. | Ontario |
| AM-PM Informatique | |
| AM/PM Mobile Solutions, Inc. | British Columbia |
| AM/PM Service Ltd | British Columbia |
| AM2D Software Systems Consulting Ltd | Ontario |
| AMA, Inc. | Ontario |
| Amabilis Software | British Columbia |
| AmacaThera | |