| Atlasopen | |
| Atlassian | New South Wales |
| Atmail | New South Wales |
| Atmo Biosciences | |
| Atmo Biosciences | |
| Atom Software | |
| Atomic Digital Marketing | New South Wales |
| Atomic Media | Victoria |
| Atomix Web & Creative Studio | South Australia |
| Atomo Diagnostics | New South Wales |
| Atrana | |
| Atronics Consulting | Victoria |
| ATS Telecoms | New South Wales |
| Attala | |
| Attendance Management Systems Pty Ltd | New South Wales |
| Atto | Victoria |
| ATU | New South Wales |
| AU Digital | New South Wales |
| Aubiz Consulting Pty Ltd | South Australia |
| AUCTUS Investment Group Ltd | Victoria |
| AudioMulch | Victoria |
| August Pty Ltd | Victoria |
| AUP IT | New South Wales |
| AuraTech Software Pty Ltd | Queensland |
| Aurion | Queensland |
| Aurita | Australian Capital Territory |
| Aurora Consulting Pty Ltd | Western Australia |
| Aus Asia Group Pty Ltd | |
| Aus Electronics Direct | New South Wales |
| AUS IT | Queensland |
| AusCERT | Queensland |
| AusDiagnostics | New South Wales |
| Ausenco Pty Ltd | |
| Ausenco Pty Ltd | |
| Ausinet | |
| Auslogics | New South Wales |
| Ausmade Hosting Services | Western Australia |
| AusNep Group Pty Ltd | |
| Ausnep IT | New South Wales |
| Auspire Web Services | Queensland |
| Aussidev Consulting | Victoria |
| Aussie Branding Solutions | |
| Aussie Digital Marketing | |
| Aussie Internet | Victoria |
| Aussie PC Fix | Australian Capital Territory |
| Aussie Webhost Pty Ltd | New South Wales |
| AussieClick | |
| Aussiecom Internet Consulting Pty Ltd | New South Wales |
| Aussies Business Apps | New South Wales |
| AussieWebHost | New South Wales |