| nVisionIT (Pty) Ltd | Gauteng |
| NWA | Gauteng |
| Nyamakop | Gauteng |
| O S S Africa CC | Western Cape |
| o5webdesign | Gauteng |
| Oasisnet | Free State |
| Obami Networks | Gauteng |
| Obsidian Systems | Gauteng |
| OceanHub Africa | Western Cape |
| Octoplus Information Solutions | Gauteng |
| Odd Digital Media | Western Cape |
| Odyssey Software | Western Cape |
| OfferZen | Western Cape |
| Office & Co | |
| OffWorld Africa (Pty) Ltd | Gauteng |
| Oficina | KwaZulu-Natal |
| OldGoat Marketing | Gauteng |
| Olsafe | |
| Olympic Communications CC | Gauteng |
| Omni Accounts | KwaZulu-Natal |
| OmniLOG | Gauteng |
| On Demand Graphic Design & Web Studio | |
| OnDesign Design and Development CC | Western Cape |
| Online By Digital | Gauteng |
| Online By Digital (Pty) Ltd | |
| Online Direct | Gauteng |
| Online Innovations | Eastern Cape |
| Online Promotions & Graphix | Gauteng |
| Online Services | KwaZulu-Natal |
| OnlineAccess Kiosks | KwaZulu-Natal |
| Onsoft (Pty) Ltd | Western Cape |
| Ooweboo | Free State |
| Open Box Software | Western Cape |
| Open Source IT Solutions CC | Gauteng |
| OpenNetworks | Gauteng |
| OPSI Systems | Gauteng |
| Opti-Num Solutions | Gauteng |
| Optic Blaze | Western Cape |
| Optimus01 | Gauteng |
| Optisphere Trading | Gauteng |
| Orange Cyberdefense South Africa | Gauteng |
| Oranje Hire Software | KwaZulu-Natal |
| Oratel Pty Ltd | Gauteng |
| Orax Solutions (Pty) Ltd | Gauteng |
| Orbit TVET College | |
| Origin Interactive | Gauteng |
| Origin Solutions | Western Cape |
| Orxy Internet | Eastern Cape |
| Osirion System Technologies | Gauteng |
| Osiris Technical Systems | Gauteng |