| Core IT | Western Australia |
| Core SEO | |
| CORE Web Systems | New South Wales |
| Corearth Australia Pty Ltd | Queensland |
| Corel Down Under, Inc. | Victoria |
| CoreNet Global | New South Wales |
| CorePlan | |
| Corexlab | |
| Corinthian Internet Services | Victoria |
| Cornerstone PM Group | New South Wales |
| Corporate Information Systems Pty Ltd | Victoria |
| Corporate Interactive | New South Wales |
| Corporate Interactive | |
| Corporate Montage | Western Australia |
| Corporate SEO | New South Wales |
| Corporate Software Australia Pty Ltd | New South Wales |
| Corporate Strategic Systems | Victoria |
| Corporate Training Solutions Australia | Queensland |
| Corporate WebSupport | South Australia |
| CorProfit | New South Wales |
| Cortex I.T. Labs Pty Ltd | Victoria |
| Corum Group Ltd | New South Wales |
| Cosmos Internet Services | Victoria |
| CoSource | |
| Cottonsoft Pty Ltd | Queensland |
| Country Capital Software | New South Wales |
| Coursebox Pty Ltd | |
| Covert | |
| CoWork Me | Victoria |
| Coxtech | New South Wales |
| COZero | |
| CP Ventures | New South Wales |
| CPAP Victoria | |
| CPT Global | Victoria |
| CQnet | Queensland |
| CQUniversity | |
| CR8VE Design | |
| Cranio Innovations Pty Ltd | |
| Crawford IT | South Australia |
| Crazy Dog Apps | New South Wales |
| Crazy Domain Names | New South Wales |
| Creately | |
| Creativ Digital Pty Ltd | |
| Creativ SEO | |
| Creative Canary | |
| Creative Chaos Pty Ltd | |
| Creative Click | |
| Creative Data Solutions | Victoria |
| Creative Development | New South Wales |
| Creative Digital Technology | New South Wales |