| AUSTAL (OSTO) LIGHTING LIMITED | Private company limited by shares | Dissolved |
| OSTOBO LIMITED | Private company limited by shares | Dissolved |
| ITALY OSTOMI INTERNATIONAL GROUP LIMITED | Private company limited by shares | Dissolved |
| FRANCE OSTON LIMITED | Private company limited by shares | Live |
| O-STONE CO., LIMITED | Private company limited by shares | Live |
| Ostone Trading Limited | Private company limited by shares | Live |
| OSTOR (HK) LIMITED | Private company limited by shares | Dissolved |
| OSTOR HONG KONG LIMITED | Private company limited by shares | Dissolved |
| Ostotec Medical Limited | Private company limited by shares | Live |
| OSTOTO CO., LIMITED | Private company limited by shares | Live |
| OSTOWN INTERNATIONAL GROUP LIMITED | Private company limited by shares | Live |