| O.N. Technology (HK) Limited | | Live |
| On2Cook Limited | Private company limited by shares | Live |
| On2Win International Co. Limited | Private company limited by shares | Dissolved |
| ONACAN CONSULTING LIMITED | Private company limited by shares | Dissolved |
| ONACO COMPANY LIMITED | Private company limited by shares | Dissolved |
| ON-ACTIVE COMPANY LIMITED | Private company limited by shares | Dissolved |
| ON-ACTIVE LIMITED | Private company limited by shares | Dissolved |
| onActivity Limited | Private company limited by shares | Live |
| ONAGA LIMITED | Private company limited by shares | Dissolved |
| ONAH INVESTMENTS LIMITED | Private company limited by shares | Live |
| ON-AIR LIMITED | Private company limited by shares | Dissolved |
| OnAir Limited | | Live |
| CYBER ON-AIR (ASIA) LIMITED | Private company limited by shares | Live |
| CHINA ON-AIR LIMITED | Private company limited by shares | Dissolved |
| CYBER ON-AIR LIMITED | Private company limited by shares | Live |
| OnAir Digital Limited | | Live |
| Language OnAir Limited | Private company limited by shares | Dissolved |
| ONAIRSHOPLINK LIMITED | Private company limited by shares | Live |
| Onairy Limited | | Live |
| ONAKA COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONALD LIMITED | Private company limited by shares | Dissolved |
| ONAMAN LIMITED | Private company limited by shares | Dissolved |
| ONAMBA (HONG KONG) LIMITED | Private company limited by shares | Dissolved |
| ONAN FAR EAST LIMITED | Private company limited by shares | Dissolved |
| ONAN SHIPPING LIMITED | Private company limited by shares | Dissolved |
| OnandOff Post-Production Limited | Private company limited by shares | Live |
| ONANDON LIMITED | Private company limited by shares | Live |
| Onandon Limited | | Live |
| ONANOFF LIMITED | Private company limited by shares | Live |
| ONANTIQUE LIMITED | Private company limited by shares | Dissolved |
| Onaon Limited | | Live |
| ONAPAL LIMITED | Private company limited by shares | Live |
| ONAPAL GOLD & JEWELLERY COMPANY LIMITED | Private company limited by shares | Dissolved |
| Onaquest HK Limited | Private company limited by shares | Live |
| ONARA COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONARE COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONARIO LIMITED | Private company limited by shares | Live |
| ONARIRO LIMITED | Private company limited by shares | Live |
| ONART COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONARY LIMITED | Private company limited by shares | Dissolved |
| ONASSIS CLOTHING COMPANY LIMITED | Private company limited by shares | Live |
| ONASSIS INTERNATIONAL LIMITED | Private company limited by shares | Live |
| ONATOKO LIMITED | Private company limited by shares | Live Commenced dormancy on 09-Sep-2009 |
| ONATOOL (HONGKONG) LIMITED | Private company limited by shares | Dissolved |
| O'NATURE CO., LIMITED | Private company limited by shares | Live |
| ONAVINI COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONAWA LIMITED | Private company limited by shares | Live |
| ONAZEN LIMITED | Private company limited by shares | Live |
| ONBAL DEVELOPMENTS LIMITED | Private company limited by shares | Dissolved |
| ONBALANCE LIMITED | | Live |
| ONBASE LIMITED | Private company limited by shares | Dissolved |
| ONBASE LIMITED | Private company limited by shares | Live |
| ONBASE GLOBAL LIMITED | Private company limited by shares | Live |
| ONBEAUTY LIMITED | Private company limited by shares | Live |
| ON-BEING COMPANY LIMITED | Private company limited by shares | Live |
| ONBENCO LIMITED | Private company limited by shares | Dissolved |
| ONBEST COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONBEST LIMITED | Private company limited by shares | Dissolved |
| ONBEST LIMITED | Private company limited by shares | Live |
| ONBEX COMPANY LIMITED | Private company limited by shares | Live |
| Onbi Limited | | Live |
| ONBIG INDUSTRIAL LIMITED | Private company limited by shares | Dissolved |
| ONBILLION INVESTMENT LIMITED | Private company limited by shares | Dissolved |
| ONBIT TRADING LIMITED | Private company limited by shares | Dissolved |
| ON-BLESS INVESTMENT LIMITED | Private company limited by shares | Dissolved |
| OnBlock Limited | Private company limited by shares | Live |
| Onbo Co., Limited | Private company limited by shares | Live |
| ONBOARD LIMITED | Private company limited by shares | Live |
| OnBoard Asia Limited | Private company limited by shares | Live |
| On-Board Consultancy Limited | | Live |
| Onboard Global Limited | Private company limited by shares | Live |
| OnBoard for Good Limited | Private company limited by shares | Live |
| OnBoard Ship Management Limited | Private company limited by shares | Live |
| PILATES ONBOARD LIMITED | | Live |
| HONG KONG ONBOLE PCB CO., LIMITED | Private company limited by shares | Live |
| ONBON JEWELLERY TRADING LIMITED | Private company limited by shares | Live |
| ONBOND LIMITED | Private company limited by shares | Live |
| ONBONG LIMITED | Private company limited by shares | Dissolved |
| ONBOTH LIMITED | Private company limited by shares | Live Ceased dormancy on 23-Apr-1998 |
| ONBRAVE LIMITED | Private company limited by shares | Dissolved |
| ONBRAVE LIMITED | Private company limited by shares | Live |
| ONBRIDGE LIMITED | Private company limited by shares | Live |
| ONBRIGHT LIMITED | Private company limited by shares | Dissolved |
| ONBRIGHT ENTERPRISES LIMITED | Private company limited by shares | Dissolved |
| ONBRIGHT ASIA (GROUP) LIMITED | Private company limited by shares | Live |
| ONBRIGHT TRADING LIMITED | Private company limited by shares | Dissolved |
| ONBURY LIMITED | Private company limited by shares | Dissolved |
| ONBUSY COMPANY LIMITED | Private company limited by shares | Dissolved |
| ONCA LIMITED | Private company limited by shares | Dissolved |
| ONCA LIMITED | | Live |
| ONCALL COMPANY LIMITED | Private company limited by shares | Live |
| Oncall E-commerce Co., Limited | Private company limited by shares | Live |
| ONCALL SOLUTIONS LIMITED | Private company limited by shares | Live |
| Oncam Asia Limited | Private company limited by shares | Live |
| ONCAPITAL LIMITED | Private company limited by shares | Live |
| ONCAPITAL INVESTMENT LIMITED | Private company limited by shares | Dissolved |
| ONCAR INDUSTRIAL CO., LIMITED | Private company limited by shares | Live |
| ONCARD LIMITED | Private company limited by shares | Live |
| ONCARE HK LIMITED | | Live |
| ON.CC LIMITED | Private company limited by shares | Live |