| One Financial Technology Ltd | Hong Kong |
| One Solution Ltd | Hong Kong |
| One Space Technology Co., Ltd | Chongqing |
| Oneflash Technology Ltd | Hong Kong |
| Oneness Biotech Co., Ltd | Taiwan |
| ONES Software Ltd | |
| ONES.CN Shenzhen Fulin Technology Co., Ltd | Guangdong |
| OneTel Hong Kong Ltd | Hong Kong |
| Onflo International Ltd | Hong Kong |
| Online Consultation | Guangdong |
| OnTheGoSystems Ltd | |
| Open Creative Ltd | Hong Kong |
| Open Systems Ltd | Hong Kong |
| Open University of Anqing (Construction Industry School of Anqing) | |
| Open University of China | Beijing |
| Open University of Fujian | |
| Open University of Hefei | |
| Open University of Kaohsiung | Taiwan |
| Open University of Nanhai | |
| Open University of Yanbian | |
| Open University of Zhangzhou | |
| OpenCart Ltd | Hong Kong |
| OpenCBS | Hong Kong |
| Ophoo Multimedia Co. | Hong Kong |
| OPNET Technologies Co., Ltd | Taiwan |
| OPRFID Technologies Ltd | Fujian |
| optify.email | Hong Kong |
| Optix Solutions Ltd | Hong Kong |
| Optotech Corporation | Taiwan |
| Optoway Technology, Inc. | Taiwan |
| Optymise | Hong Kong |
| Oracle (China) Co., Ltd | Beijing |
| Oracle Hong Kong | Hong Kong |
| Oracle Taiwan | Taiwan |
| OranssiBio (Shanghai) Co., Ltd | |
| Orbit Startups | Shanghai |
| OrbusNeich Medical Co., Ltd | Hong Kong |
| Ordos Institute of Technology | |
| ORI Capital | |
| Oricell Therapeutics | |
| Orienspace | |
| Orient Semiconductor Electronics Ltd | Taiwan |
| Orient Supply Instruments Ltd | Hong Kong |
| Oriental System Technology, Inc. | Taiwan |
| Oriente | Hong Kong |
| Origin Quantum Computing Technology (Hefei) Co., Ltd | Anhui |
| Original Online | |
| OriginBit Ltd | Hong Kong |
| Orvibo, Inc. | |
| OsChina.NET | Beijing |