| CIO New Zealand | New South Wales |
| CipherLab Australia Pty Ltd | New South Wales |
| CipherTel Pty Ltd | Western Australia |
| Circle Media | |
| CircleBC | |
| CircleLabs | |
| Cirrus Real Time Processing Systems Pty Ltd | New South Wales |
| Citadel Computer Systems | New South Wales |
| Citadel Group Ltd | Australian Capital Territory |
| Citadel Technology Solutions | Australian Capital Territory |
| CitrusAd | Queensland |
| City Systems Pty Ltd | New South Wales |
| Cky Media Website design | |
| Claiming.com.au | Victoria |
| ClamWin | New South Wales |
| Clarinet Internet Solutions | Victoria |
| Clarinox | Victoria |
| Clarity Pharmaceuticals | |
| Class Pty Ltd | New South Wales |
| Class Training | New South Wales |
| Clear Networks | Victoria |
| Clear Pixel | Queensland |
| Clearwater Agency | |
| Clemenger BBDO | |
| Clemenger Group Ltd | New South Wales |
| Cleo Diagnostics Ltd | |
| Clever Clicks | New South Wales |
| Clever Culture Systems | |
| Clever Starfish | Western Australia |
| CleverClicks | |
| Clevvi | Queensland |
| Click Click Media | |
| Click Creative | |
| Click Studios (SA) Pty Ltd | South Australia |
| Click Trends | |
| Click-me-it | Victoria |
| Click2it | New South Wales |
| Clickmatix Pty Ltd | |
| Clicks IT Recruitment | Victoria |
| Clik Digital | |
| Clinuvel Pharmaceuticals Ltd | |
| Clipchamp | |
| Clix Computer Centre | New South Wales |
| Clixpert Pty Ltd | |
| Clixx.io Pty Ltd | New South Wales |
| ClockOn Australia | New South Wales |
| Cloud Assembly | Queensland |
| Cloud Concepts | New South Wales |
| Cloud Downunder | |
| Cloud Made Simple - IT Consultants | Victoria |