| Crendal Computing international Pty Ltd | New South Wales |
| Criticone | Victoria |
| CRM Online Australia Pty Ltd | Western Australia |
| CRN Australia | New South Wales |
| CrossBar Media | New South Wales |
| Crow Clinical | Queensland |
| Crucial Paradigm Pty Ltd | New South Wales |
| Crunchy Digital | |
| Crux Biolabs Pty Ltd | Victoria |
| Crypto Head Pty Ltd | Queensland |
| Crypto SA | South Australia |
| Cryptocate | South Australia |
| CryptoSpend | New South Wales |
| Crystal IT | Queensland |
| CSE Technology Pty Ltd | New South Wales |
| CSIRO | Australian Capital Territory |
| CSL Behring | Victoria |
| CSO Australia | New South Wales |
| CTI Recruitment | New South Wales |
| Cube Exchange Australia Pty Ltd | |
| Cultivate Digital | Victoria |
| Culture Amp Pty Ltd | Victoria |
| Curicon Pty Ltd | |
| Curious Thing AI | |
| Currinda Pty Ltd | Victoria |
| Currus Biologics Pty Ltd | Victoria |
| Curtin College | |
| Curtin University | Western Australia |
| Curtin University - Department of Computing | Western Australia |
| Curtin University - School of Electrical Engineering, Computing and Mathematical Sciences | Western Australia |
| Curtin University of Technology - Electrical and Computer Engineering | Western Australia |
| Custom Easy Pty Ltd | New South Wales |
| CXi Software Pty Ltd | Victoria |
| Cyanweb | Western Australia |
| Cyber Interchange Australia | New South Wales |
| CyberHound Pty Ltd | Queensland |
| Cybernet Evolution Pty Ltd | Queensland |
| CyberSecOn Pty Ltd | Victoria |
| CyberShack | New South Wales |
| Cygnet Securities Australia Pty Ltd | Victoria |
| Cymax Pty Ltd | Queensland |
| Cynata Therapeutics | Victoria |
| Cynch Sec Pty Ltd | Victoria |
| Cynergic Pty Ltd | Victoria |
| Cypher Research Laboratories Pty Ltd | Queensland |
| CyRise | Victoria |
| Cyrius Media Group Pty Ltd | New South Wales |
| D-Link Australia | New South Wales |
| D.P. Web Design | Queensland |
| D.R.A. Computing Pty Ltd | South Australia |