| Ocean Impact Organisation | New South Wales |
| Ocean Office Automation Pty Ltd | New South Wales |
| Ocean Software | Victoria |
| Oceania Polytechnic Institute of Education | |
| Ocom Software | Victoria |
| Octet | New South Wales |
| October Productions | |
| Octopus Deploy | Queensland |
| Octopusbot | New South Wales |
| Offground | Victoria |
| Office Automation Pty Ltd | Western Australia |
| Office Information Australia | Western Australia |
| Office of the Australian Information Commissioner | New South Wales |
| Offis Pty Ltd | New South Wales |
| OFX | |
| Ohio Digital | |
| OKI Data (Australia) | New South Wales |
| Olivitek Software Pty Ltd | Victoria |
| OMC International Pty Ltd | Victoria |
| OMG! Creative | Victoria |
| OmniHyper | New South Wales |
| Omninet | Western Australia |
| Omny Studio | Victoria |
| On Data | |
| On Deck Capital Australia Pty Ltd | New South Wales |
| On Q Recruitment | New South Wales |
| OncoRes Medical Pty Ltd | Western Australia |
| OncoSil Medical Ltd | New South Wales |
| Ondetto | |
| One AML Review Pty Ltd | New South Wales |
| ONE BCG Pty Ltd | New South Wales |
| One World Media | |
| One10 | Victoria |
| Oneit.com.au | Western Australia |
| OneMD | New South Wales |
| OneVentures Pty Ltd | New South Wales |
| Online Advantage | New South Wales |
| Online Marketing Gurus | New South Wales |
| Online Visions | Queensland |
| OnlineConsulting.com.au Pty Ltd | New South Wales |
| OnMyWeb | New South Wales |
| Onpoint Creations | New South Wales |
| OntheNet | Queensland |
| Ontologics Pty Ltd | Queensland |
| Op Central | Victoria |
| Opacity Design | New South Wales |
| Open Copy | Western Australia |
| Open Money Group Pty Ltd | New South Wales |
| Open Source Industry Australia Ltd | Australian Capital Territory |
| Open Spatial Pty Ltd | New South Wales |