| PROTOCOL LIMITED | Private company limited by shares | Dissolved |
| NEW PROTOCOL LIMITED | Private company limited by shares | Live |
| PROTOCOL V LIMITED | Private company limited by shares | Dissolved |
| PROTOCOL B LIMITED | Private company limited by shares | Dissolved |
| PROTOCOL S LIMITED | Private company limited by shares | Dissolved |
| PROTOCOL COMPANY LIMITED | Private company limited by shares | Dissolved |
| BOX PROTOCOL LIMITED | Private company limited by shares | Live |
| Ola Protocol Limited | | Live |
| KIP Protocol Limited | | Live |
| PROTOCOL CENTURY LIMITED | Private company limited by shares | Dissolved |
| Protocol Direct Dialing Limited | Private company limited by shares | Dissolved |
| Duchamp Protocol Limited | Private company limited by shares | Live |
| ENTERPRISE PROTOCOL LIMITED | Private company limited by shares | Dissolved |
| First Protocol Limited | Private company limited by shares | Dissolved |
| GTGOLD PROTOCOL LIMITED | | Live |
| Elite Protocol Hong Kong Company Limited | Private company limited by shares | Live |
| Initial Assessment Protocol Limited | Private company limited by shares | Live |
| KONNECT PROTOCOL LIMITED | | Live |
| PROTOCOL RESEARCH LIMITED | Private company limited by shares | Live |
| PROTOCOL RESOURCES HK LIMITED | Private company limited by shares | Dissolved |
| SWAP PROTOCOL LIMITED | Private company limited by shares | Live |
| PROTOCOL VOIP LIMITED | Private company limited by shares | Dissolved |