| ONESING 2020998 · TMA1157956 | Shenzhen Suruiketa Technology Co. Ltd | 25 Clothing | Registered | 2022 |
| ONESUN 1827591 · TMA1013821 · design | Alternative Eyewear Inc. | 9 Electronics | Registered | 2019 |
| ONOSONIC 2236736 · design | Owner not listed | 21 Housewares | Pending | 2022 |
| 1ONESAND 2006293 | BRAMPTON BRICK LIMITED/ BRIQUE BRAMPTON LIMITÉE | 19 Building | Pending | 2020 |
| 1ONESAND 2006286 · design | BRAMPTON BRICK LIMITED/ BRIQUE BRAMPTON LIMITÉE | 19 Building | Pending | 2020 |
| 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 |
| ONSEN 1954250 · TMA1192262 · design | NuEnergy Distribution Inc. | 11 Lighting | Registered | 2023 |
| ONESAM 1910330 · TMA1086840 · design | Guangzhou Zheng Gong Niu Technology Co. Ltd. | 9 Electronics | Registered | 2020 |
| ONEGIN 1708158 · TMA1036834 | Owner not shown | 32 Beer33 Wine35 Advertising+2 | Registered | 2019 |
| ONESUMX 1698410 · TMA979174 | Owner not shown | 35 Advertising36 Finance42 Science+1 | Registered | 2017 |
| 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 |
| ONEZONE 2272756 | SPEC FURNITURE INC. | 6 Metal19 Building20 Furniture+4 | Pending | 2023 |
| ONEZONE 2060213 | Global Resources International, Inc. | 10 Medical | Pending | 2020 |
| OMNISONIC 1851376 · TMA1072132 | Microsoft Corporation | 9 Electronics | Registered | 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 |