| Signal Direct Communications | Saskatchewan |
| Signal Integrity Electronics | British Columbia |
| SignalChem Biotech, Inc. | |
| Signature Design Communication | |
| SIGnature Recruiting, Inc. | |
| SignatureWEB | Quebec |
| Signé François Roy, Inc. | Quebec |
| Signet Studio Design, Inc. | British Columbia |
| Signority | |
| Signup Systems Ltd | British Columbia |
| SigScale Global, Inc. | |
| Silect Software, Inc. | Ontario |
| Silecta, Inc. | Ontario |
| Silent Domains | |
| Silent Partner Software, Inc. | Quebec |
| Silentblast, Inc. | Ontario |
| Silicon Direct | Ontario |
| Silicon Solutions | British Columbia |
| SiliconUnlimited Computer Services, Inc. | Alberta |
| Sillworks | Ontario |
| Silo Communication | Quebec |
| SiLQ Connect | |
| Silstone Health | |
| Silvacom Ltd | |
| Silvatech Consulting Ltd | British Columbia |
| Silver Barrel Solutions | British Columbia |
| Silver Maple Communications | Quebec |
| Silver Software | Ontario |
| Silver Touch Technologies Canada Ltd | |
| Silverback Productions | Nova Scotia |
| SilverBlaze | Ontario |
| SilverCreek Software Ltd | |
| Silverfox Designs | Saskatchewan |
| Silverjack Studio | Quebec |
| SilverJax Web Solutions | Alberta |
| Silverorange | Prince Edward Island |
| SilverServers, Inc. | British Columbia |
| Silvertip Software | British Columbia |
| SilverWare POS | Ontario |
| SimActive | Quebec |
| Simalam, Inc. | Ontario |
| Simberon, Inc. | Ontario |
| Simbi | |
| Simbol Test Systems, Inc. | Quebec |
| SIMCO Technologies | Quebec |
| Simcoe IT | |
| SIMCOM | Ontario |
| Simcona Electronics | Ontario |
| Simex Defence, Inc. | |
| Simgraph | Quebec |