| Cicada Security Technology | Quebec |
| Cie-tech, Inc. | Quebec |
| Ciena | Ontario |
| CieNOV | |
| CIFAR | Ontario |
| Cifelli Corporation | Ontario |
| Cigogne Technologies | Quebec |
| CIIBIS, Inc. | Alberta |
| CIK Audio Vidéo | Quebec |
| CIK Telecom, Inc. | Ontario |
| Cilex | |
| Cimetech International, Inc. | Quebec |
| CIMSOFT | |
| CimsonTT | Ontario |
| CIMTECH | Quebec |
| Cimtel | Quebec |
| Cinchy | Ontario |
| Cincom Systems | Ontario |
| Cineapps | Quebec |
| Cinetic Communication | Quebec |
| Cinotec | |
| Cintek Internet Services Ltd | British Columbia |
| CIO Association of Canada | Ontario |
| Cionex | Ontario |
| CIP Office Technology | Alberta |
| CIPC, Inc. | Quebec |
| Cipherify | |
| Ciranna Technologie, Inc. | |
| Circa Enterprises, Inc. | Alberta |
| Circa Information Corporation | Ontario |
| CircaMax | Alberta |
| Circle Cardiovascular Imaging, Inc. | |
| Circle Graphics | British Columbia |
| Circle Neurovascular Imaging, Inc. | Alberta |
| Circonference Québec | Quebec |
| Circuit 9 | |
| Circuit Design Corporation | Quebec |
| Circuit Plus, Inc. | Ontario |
| Circuit Stream | Alberta |
| Circuit Test Electronics | British Columbia |
| Circuit-Tech, Inc. | Ontario |
| Circuits Central, Inc. | Ontario |
| Circumference Technology Services | |
| CircumPoint Software Ltd | British Columbia |
| Ciris | Quebec |
| Cirrus Tech Ltd | Ontario |
| Cirta Intercom | Quebec |
| Cisco Systems Canada Co. | Ontario |
| Cision Canada | |
| CISM Gestion Informatique, Inc. | Quebec |