| ONSON 2032896 · TMA1139663 | Shenzhen Weizhisheng E-Commerce Co.Ltd. | 7 Machines | Registered | 2022 |
| ONSON 2003667 · TMA1143464 · design | Shenzhen Weizhisheng E-Commerce Co.Ltd. | 7 Machines | Registered | 2022 |
| OneOcean 2238563 | OneOcean Group Limited | 9 Electronics16 Paper35 Advertising+5 | Pending | 2022 |
| ONOSONIC 2236736 · design | Owner not listed | 21 Housewares | Pending | 2022 |
| ONCOONE 2003628 · TMA1127198 | OncoOne Research & Development GmbH | 5 Pharmaceuticals42 Science44 Medical | Registered | 2022 |
| ONEXONE 1357631 · TMA772818 | ONEXONE Foundation | 14 Jewellery25 Clothing | Registered | 2010 |
| ONEXONE 1351887 · TMA717690 · design | ONEXONE Foundation | 35 Advertising | Registered | 2008 |
| ONEXONE 1260745 · TMA664818 | ONEXONE Foundation | 35 Advertising | Registered | 2006 |
| OMNICOM 1141918 · TMA596637 | Omnicom Translations Inc. | 40 Treatment41 Education | Registered | 2003 |
| ONEZONE 2272756 | SPEC FURNITURE INC. | 6 Metal19 Building20 Furniture+4 | Pending | 2023 |
| ONSCENT 2213725 | Premier Specialties, Inc. | 1 Chemicals3 Cosmetics4 Oils+4 | Pending | 2022 |
| ONEJOON 2123569 | ONEJOON GmbH | 7 Machines11 Lighting42 Science | Pending | 2021 |
| ONEZONE 2060213 | Global Resources International, Inc. | 10 Medical | Pending | 2020 |
| OMEGAMAZING 2212477 · TMA1243116 | Vibrant Health Products Inc. dba Silver Hills Bakery | 30 Coffee35 Advertising43 Restaurants | Registered | 2024 |
| Omzanclo 2188197 · TMA1282711 | CELLTRION, INC. | 5 Pharmaceuticals | Registered | 2025 |
| ONSEMI 2163807 · TMA1197147 · design | SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC | 9 Electronics40 Treatment42 Science | Registered | 2023 |
| ONSEMI 2162326 · TMA1196045 | SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC | 9 Electronics40 Treatment42 Science | Registered | 2023 |
| OMNISMART 2146610 · TMA1187769 | HONEYWELL INTERNATIONAL INC. | 9 Electronics | Registered | 2023 |
| OMEGANOMIX 2142609 · TMA1200382 | an individual | 20 Furniture | Registered | 2023 |
| OMEGANOMIC 2142608 · TMA1200381 | an individual | 20 Furniture | Registered | 2023 |
| ONEAGENT 2141675 · TMA1250808 | Dynatrace LLC | 9 Electronics | Registered | 2024 |
| OneCem 2134167 · TMA1240962 | Holcim Technology Ltd | 19 Building | Registered | 2024 |
| OWANQIANG 2131450 · TMA1194321 | Shenzhen Heliliang Electronic Commerce Co. Ltd. | 11 Lighting | Registered | 2023 |
| ONSUMCO 2116225 · TMA1183023 | an individual | 5 Pharmaceuticals | Registered | 2023 |
| OMWEEKEND 2101656 · TMA1155469 · design | FOKDA POPO PTE LTD | 35 Advertising | Registered | 2022 |