| OXWELL 2049718 · TMA1166745 | Oxwell Group Inc. | 5 Pharmaceuticals | Registered | 2023 |
| Oxseal 2194679 | 13989402 Canada Inc. | 17 Rubber | Pending | 2022 |
| OSCAL 2075366 · TMA1162551 · design | Shenzhen DOKE Electronic Co. Ltd. | 9 Electronics | Registered | 2023 |
| OCL 1821855 · TMA1009278 · design | OCL Group Inc | 35 Advertising37 Construction39 Transport+2 | Registered | 2018 |
| OXELO 1798361 · TMA994990 | Owner not shown | 9 Electronics18 Leather25 Clothing+1 | Registered | 2018 |
| OCAL 1668558 · TMA922973 | ABB Asea Brown Boveri Ltd. | 6 Metal9 Electronics | Registered | 2015 |
| OXELO 1609555 · TMA968271 | Owner not shown | 28 Toys35 Advertising | Registered | 2017 |
| OCIL 1596322 · TMA889109 | Oil Casualty Insurance Ltd. | 36 Finance | Registered | 2014 |
| OXLEY 1399701 · TMA818485 · design | Bacardi & Company Limited (a corporation organized and existing under the laws of the Principality of Liechtenstein) | 33 Wine | Registered | 2012 |
| OOCL 1125528 · TMA601439 · design | Orient Overseas Container Line Limited | 35 Advertising39 Transport45 Legal | Registered | 2004 |
| OOCL 1125526 · TMA596484 | Orient Overseas Container Line Limited | 35 Advertising39 Transport45 Legal | Registered | 2003 |
| OCCOL 2161713 | Cabinetapp Inc. | 9 Electronics | Pending | 2022 |
| OCELO 1965889 | 3M Company | 21 Housewares | Pending | 2019 |
| OSCELLA 1878742 · TMA1064796 | Synthetic Genomics, Inc. | 9 Electronics42 Science | Registered | 2019 |
| OKLA 2251459 · TMA1270123 · design | Owner not listed | 12 Vehicles | Registered | 2024 |
| Ozuly 2243083 · TMA1263027 | Owner not listed | 9 Electronics | Registered | 2024 |
| OCULO 2238849 · TMA1254222 | Effcon Laboratories, Inc. | 5 Pharmaceuticals | Registered | 2024 |
| OUGELEE 2233505 · TMA1255273 | an individual | 11 Lighting | Registered | 2024 |
| Ousaliyea 2204044 · TMA1240037 | Guangzhou Ouyes Trading Co., Ltd. | 16 Paper | Registered | 2024 |
| OGLO 2194646 · TMA1235154 | 2301114 Alberta Ltd. | 9 Electronics11 Lighting | Registered | 2024 |
| Ousaliyea 2177203 · TMA1230147 | Guangzhou Ouyesi Trading Co. Ltd. | 9 Electronics | Registered | 2024 |
| OUXUL 2172578 · TMA1223136 | an individual | 9 Electronics | Registered | 2024 |
| OGL 2165861 · TMA1213390 · design | Guangzhou Dongchen Zhizao Supply Chain Co. LTD. | 25 Clothing | Registered | 2023 |
| Osailou 2147503 · TMA1204120 | Shenzhen Yunlaijun Technology Co. , Ltd. | 25 Clothing | Registered | 2023 |
| ouxile 2142174 · TMA1200357 | Hangzhou Chucheng Electronic Commerce Co. Ltd. | 25 Clothing | Registered | 2023 |