| Name | Region |
|---|---|
| OnGrid Systems | Moscow |
| Oninetours | |
| OnlineHoster.net | Crimea |
| Only4soft | Moscow |
| OnlyCom | Moscow |
| ONPRO.RU | Moscow |
| OOO "Rollersoft" | Belgorod |
| OOO "Visor" | Kemerovo |
| OOO "АДС" | Perm |
| OOO "Дилинг" | Moscow |
| OOO «Гепатера» | |
| OOO «Инлексис» | |
| OPCserver.ru | Moscow |
| Open Systems | Voronezh |
| OpenNET | |
| OPENservices | |
| Optimism.ru, LLC | Moscow |
| Optimo.ru | Moscow |
| Optimum Web Service Agency | Moscow |
| Optio Soft JSC | Moscow |
| Oracle Россия | Moscow |
| Orange Code | |
| Orbitika.ru | Moscow |
| Oscar Soft | Moscow |
| OSDART, Inc. | |
| OSRSoft | Perm |
| Ostrovok.ru | |
| OTCEK.com | Yamalo-Nenets |
| Overmobile | |
| Oxygen Forensics | Moscow |
| Ozon | |
| PalmShop.ru | Moscow |
| Palмагазин | Moscow |
| Paradigma Soft | |
| PascalABC.NET | Rostov |
| Passcovery | |
| Pay2u | |
| PayMe | |
| PayOnline | |
| PC Shop | Moscow |
| Pc-users.ru | Moscow |
| PC1 | Moscow |
| PCSoft-Shop | Moscow |
| Perm State University | Perm |
| Perpetuum Software, LLC | Altai |
| Pharmstandard JSC | |
| Pharmsynthez | |
| Photosoft | Moscow |
| PHP Development | |
| PHP.su | Moscow |