| Optimised | |
| Optimising Pty Ltd | Victoria |
| Optiscan Imaging Ltd | |
| Optominds | |
| Oracle Corporation Australia Pty Ltd | New South Wales |
| Oracle Digital | |
| Oracle-AI | |
| OracleStudio Pty Ltd | Queensland |
| Orange Digital | Queensland |
| Orbital8 Pty Ltd | Victoria |
| Orbitek Digital Solutions | |
| Ordermentum | New South Wales |
| OrdinaryAgency | |
| Organik.services | Victoria |
| Organise Internet | |
| Orient Capital Pty Ltd | New South Wales |
| Origen Software Pty Ltd | |
| Orion Creative | |
| Orion Satellite Systems Pty Ltd | Western Australia |
| OrionVM | |
| Orite IT Solutions | New South Wales |
| Orro Pty Ltd | New South Wales |
| Ortabe Pty Ltd | New South Wales |
| Orthocell Ltd | Western Australia |
| OscarPOS | |
| OSHatWork | Western Australia |
| OSINT Combine | New South Wales |
| Osky | |
| Our Community House | Victoria |
| Out in the Clouds | |
| Outcomex | New South Wales |
| Outsource2Us | |
| Outsourced HR Solution | |
| Overflow Internet | Queensland |
| OvertheWire Pty Ltd | Queensland |
| Owls Agency Pty Ltd | |
| Ozbiz PCLawyer | New South Wales |
| Ozdoc | Queensland |
| Ozehosts.com | Western Australia |
| OzeVision Pty Ltd | Australian Capital Territory |
| Ozgene Pty Ltd | Western Australia |
| OzGuide Internet & Computer Solutions | Victoria |
| OzHosting.com Pty Ltd | New South Wales |
| OzISP | Victoria |
| Oziti Web Design | Western Australia |
| Ozius Spatial | Western Australia |
| OzLocal Australia | |
| OZNET IT & Media Services | New South Wales |
| Ozone Team | |
| OZtell | New South Wales |