| Online Designs | |
| OnlineSale Computers | Auckland |
| OnlyDomains | Hawke's Bay |
| Onsite Support Ltd | |
| Ontrack Software Ltd | |
| Opcode | Wellington |
| Opem Print Solutions Ltd | Wellington |
| Open Polytechnic | Wellington |
| Opmetrix | Canterbury |
| OpsCentre | |
| Optimal Workshop Ltd | |
| Optimation Group | Wellington |
| Optimum Marketing Ltd | Wellington |
| Optimus Systems Ltd | Auckland |
| Optimyze | |
| Oracle New Zealand | Auckland |
| Oraco Solutions Ltd | Waikato |
| Orange Direct | Auckland |
| Orbica | Canterbury |
| Orbits IT Solution Ltd | Auckland |
| Orbus | |
| OrcaCom Ltd | Auckland |
| Orchid | Auckland |
| ORCL Toolbox Ltd | Auckland |
| Orcon | Auckland |
| Original Image Ltd | Auckland |
| Orion PCs | |
| Oritain | |
| Orrin Technology Ltd | |
| Oryx Technologies Ltd | Wellington |
| OSL Software | Auckland |
| OSS Group | Auckland |
| Otago Business Equipment | |
| Otago Polytechnic | Otago |
| Otago Polytechnic - Information Technology | Otago |
| Our School Ltd | Auckland |
| OurCloud | |
| Out & In | |
| Outasight Marketing | |
| Outreach Software Ltd | |
| Outwide Ltd | Wellington |
| Overclockers New Zealand | Canterbury |
| Overdose | |
| Oystercatcher Design Ltd | Canterbury |
| Pacific Blue Software | |
| Pacific Channel | Auckland |
| Pacific Edge Ltd | Otago |
| Pacific International Hotel Management School | |
| Pacific Technology Solutions | Waikato |
| Packet Technologies Ltd | Auckland |