| OREweb.ca | Ontario |
| Orex Media | |
| Orfé | Quebec |
| Organimi | Ontario |
| Organisation Universitaire Interaméricaine | Quebec |
| Organized Assistant | Ontario |
| Oricom | Quebec |
| Orient Computer | British Columbia |
| Orient Display Ltd | Ontario |
| Orientation Travail | |
| Orientech | Quebec |
| Origam.ai | |
| Origami | |
| Origami Accounting, Inc. | Quebec |
| Original Ginger | British Columbia |
| Original Web Ventures | British Columbia |
| Original-Fly Multimedia Corporation | Ontario |
| Originality.ai | |
| Orijine | Quebec |
| Orillia ProNet, Inc. | Ontario |
| Orinatek.ca | Quebec |
| Orion Biotechnology Canada Ltd | |
| Orion Canada, Inc. | Ontario |
| Orion Cybernetics | Ontario |
| Orion eSolutions | |
| Orion Software | |
| Orium | |
| Orius Technologies | Quebec |
| Orizon | |
| Orizon Mobile | Quebec |
| OrizonMédia | Quebec |
| Ormuco, Inc. | Quebec |
| Orogin Studios | Ontario |
| OroLogic, Inc. | Quebec |
| Oromocto & Area Chamber of Commerce | |
| ORP.ca | Ontario |
| Orphic Agence Web | |
| Orqid Design | |
| OrRouge | Quebec |
| Ortech, Inc. | |
| Orthogone Technologies, Inc. | |
| Orvitek, Inc. | Ontario |
| OS4 Techno | Quebec |
| Ose Design | Quebec |
| Osedea, Inc. | Quebec |
| Osela, Inc. | |
| Osellus, Inc. | Ontario |
| OSF Digital | Quebec |
| Oshara, Inc. | Quebec |
| Oshki-Wenjack | |