| Centre for Quantum Computation and Communication Technology | New South Wales |
| Centrix | New South Wales |
| Century Software Pty Ltd | New South Wales |
| Cerebiz Pty Ltd | South Australia |
| Cerebrum (Australia) Pty Ltd | Victoria |
| Certa Therapeutics | |
| Certane Group Pty Ltd | Victoria |
| Cevo (VIC) Pty Ltd | Victoria |
| Challenger Group Ltd | New South Wales |
| Chameleon Software Pty Ltd | Western Australia |
| Chamonix IT Consulting | South Australia |
| Chaos Theory Games Pty Ltd | New South Wales |
| ChargeDesk Pty Ltd | New South Wales |
| Charles Darwin University | Northern Territory |
| Charles Elena | |
| Charles Sturt University | New South Wales |
| Charles Sturt University - School of Computing and Mathematics | New South Wales |
| Chart Gantt | Victoria |
| Chatstack | Queensland |
| Cheap Chips | Queensland |
| CheapDomains.com.au | New South Wales |
| CheckDog | New South Wales |
| Cheltenham Group | Western Australia |
| ChiefDreamer | Queensland |
| Children's Medical Research Institute | |
| Children’s Cancer Institute | |
| Chill IT Pty Ltd | |
| Chimeric Therapeutics Ltd | |
| Chironix | |
| Chisel Software | South Australia |
| Chisholm Institute | |
| Chittagong IT Solutions | |
| Choc Chip Digital | |
| Chook Digital Pty Ltd | |
| ChordWizard Software Pty Ltd | New South Wales |
| Chorus Design | New South Wales |
| Chris McIntosh Design | New South Wales |
| Chris Sutherland Australia | |
| Chriscore.net | Victoria |
| Christian Heritage College | |
| Christie Spaces Pty Ltd | New South Wales |
| Christom Pty Ltd | Victoria |
| Christopher Strong Design | Victoria |
| Chromatix | Victoria |
| ChronoBank | New South Wales |
| CIBIS International | New South Wales |
| Cicada Innovations | New South Wales |
| Cierrena | |
| Cingulan Space | |
| CIO Australia | New South Wales |