| Optikosmedia | Quebec |
| Optilog Compagnie de Gestion, Inc. | Quebec |
| Optima Aero | |
| Optima Diagnostics | |
| OPTIMA IT Consulting | Ontario |
| Optima Systems, Inc. | Manitoba |
| Optima Telecom, Inc. | Ontario |
| Optimal Arc Web Development | British Columbia |
| Optimal Data Group, Inc. | Ontario |
| Optimec Consultants | |
| Optimicro Technologies, Inc. | Ontario |
| Optimiser Infotech Software Solutions | |
| Optimity | Ontario |
| Optimized Consulting, Inc. | Ontario |
| Optimized Webmedia Marketing | British Columbia |
| Optimset | Ontario |
| Optimum Conseil | Quebec |
| Optimum Instruments, Inc. | Alberta |
| Optimum-Canada | |
| OptimumWeb, Inc. | |
| Optimus Information, Inc. | British Columbia |
| Optina | |
| Optinet Systems | British Columbia |
| Option Industrial Computers | Quebec |
| Option Technique, Inc. | Quebec |
| OPTIS Ingénierie | |
| Optitech Solutions systèmes | Quebec |
| Optithera | |
| Optiva | Ontario |
| Optiwave Systems, Inc. | Ontario |
| OptiWeb Marketing | |
| Optiweb Media | |
| Optix | |
| Optmalon Software | Ontario |
| Optonique | |
| Optosys | Quebec |
| Optrics Engineering | Alberta |
| Optum Engineering, Inc. | Ontario |
| Opulent Castle | |
| Opus 1 Music, Inc. | British Columbia |
| Opus Communication, Inc. | Ontario |
| Opus Computer Solutions | Manitoba |
| OPUS Consulting Group Ltd | |
| Opus2 Mobile Solutions | Ontario |
| OpusHS | Saskatchewan |
| Oracast | Alberta |
| Oracle Canada | Ontario |
| Oraclexperts | Quebec |
| Orange Digital Marketing, Inc. | Ontario |
| ORANGE Digital Systems, Inc. | Quebec |