| ONEHOME 2037000 · TMA1224151 | CoreLogic Solutions, LLC | 42 Science | Registered | 2024 |
| ONEOME 1699217 · TMA925731 | ONEOME LLC | 42 Science44 Medical | Registered | 2016 |
| ONYONE 0838599 · TMA526661 · design | ONYONE CO. LTD. | 25 Clothing28 Toys | Registered | 2000 |
| ONEON 2268255 · design | Mover Cross-border E-commerce Shenzhen Co.Ltd | 8 Hand | Pending | 2023 |
| ONine 2162680 · TMA1212320 | Shenzhen Lingdu Yanxuan Electronic Business Co. Ltd. | 16 Paper | Registered | 2023 |
| OENON 1670948 · TMA1057365 · design | Oenon Holdings, Inc. | 1 Chemicals4 Oils5 Pharmaceuticals+2 | Registered | 2019 |
| OEMINE 1311221 · TMA745672 | an individual | 3 Cosmetics5 Pharmaceuticals16 Paper | Registered | 2009 |
| ONENO 2283498 | an individual | 25 Clothing | Pending | 2023 |
| OMNIONE 2281228 | Billi R & D Pty Ltd | 11 Lighting | Pending | 2023 |
| OuMuaMua 2220880 · TMA1248546 | NanJing Chuang Qing Dian Zi Shang Wu Co.,Ltd | 28 Toys | Registered | 2024 |
| Omino 2103852 · TMA1190675 | Olight Group Co.Ltd | 9 Electronics | Registered | 2023 |
| Omaeon 2066302 · TMA1157389 | an individual | 11 Lighting | Registered | 2022 |
| OHMIUM 2057652 · TMA1149239 | Ohmium International, Inc. | 1 Chemicals9 Electronics11 Lighting+1 | Registered | 2022 |
| ONEYIM 1999845 · TMA1127096 | Owner not shown | 24 Textiles | Registered | 2022 |
| OMEN 1991715 · TMA1092030 | HP Hewlett Packard Group LLC | 9 Electronics18 Leather | Registered | 2021 |
| OMEN 1985138 · TMA1072436 | HP Hewlett Packard Group LLC | 20 Furniture | Registered | 2020 |
| OMUM 1974105 · TMA1137176 | an individual | 3 Cosmetics44 Medical | Registered | 2022 |
| OOMOMO 1967753 · TMA1192277 | 9926585 Canada Ltd. | 30 Coffee | Registered | 2023 |
| +OMNIUM 1913378 · TMA1183431 | an individual | 7 Machines9 Electronics12 Vehicles+6 | Registered | 2023 |
| OMNIUM 1913377 · TMA1148342 | an individual | 7 Machines9 Electronics12 Vehicles+6 | Registered | 2022 |
| OOMOMO 1851553 · TMA1011179 | 9926585 Canada Ltd. | 35 Advertising | Registered | 2018 |
| OMNIOME 1840706 · TMA1070017 | Omniome, Inc. | 1 Chemicals9 Electronics10 Medical+1 | Registered | 2020 |
| OMNIUM 1798159 · TMA982351 | Owner not shown | 5 Pharmaceuticals | Registered | 2017 |
| OMOM 1754089 · TMA962220 · design | CHONGQING JINSHAN SCIENCE & TECHNOLOGY (GROUP) CO. LTD. | 10 Medical | Registered | 2017 |
| ONOMIE 1684159 · TMA1032732 | MAKEFIELD LLC | 3 Cosmetics5 Pharmaceuticals35 Advertising | Registered | 2019 |