| OMNIJOIN 1624299 · TMA944382 | BROTHER INDUSTRIES, LTD. | 9 Electronics38 Telecommunications | Registered | 2016 |
| 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 |
| ONCOONE 2003628 · TMA1127198 | OncoOne Research & Development GmbH | 5 Pharmaceuticals42 Science44 Medical | Registered | 2022 |
| ONESUN 1827591 · TMA1013821 · design | Alternative Eyewear Inc. | 9 Electronics | Registered | 2019 |
| ONEGIN 1708158 · TMA1036834 | Owner not shown | 32 Beer33 Wine35 Advertising+2 | Registered | 2019 |
| 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 |
| OMISOON 2301168 | Guangdong Shunde NOON Electrical Appliance Manufacturing Co. Ltd | 11 Lighting | Pending | 2023 |
| ONEZONE 2272756 | SPEC FURNITURE INC. | 6 Metal19 Building20 Furniture+4 | Pending | 2023 |
| ONOCON 2095727 · design | Onocon Developments Ltd. | 36 Finance37 Construction39 Transport+1 | Pending | 2021 |
| ONZOOM 2073558 | Zoom Communications, Inc. | 9 Electronics35 Advertising42 Science | Pending | 2020 |
| ONEZONE 2060213 | Global Resources International, Inc. | 10 Medical | Pending | 2020 |
| ONEAGENT 2141675 · TMA1250808 | Dynatrace LLC | 9 Electronics | Registered | 2024 |
| ONECONTENT 1955730 · TMA1267664 | HYLAND SOFTWARE, INC. | 9 Electronics42 Science | Registered | 2024 |
| ONECONNECT 1769034 · TMA1037355 | Panasonic Corporation of North America | 35 Advertising38 Telecommunications41 Education | Registered | 2019 |
| ONECOMMAND 1448639 · TMA832447 | Emulex Design & Manufacturing Corporation | 9 Electronics | Registered | 2012 |
| ONECONNECT 1448638 · TMA832448 | Emulex Design & Manufacturing Corporation | 9 Electronics | Registered | 2012 |
| OniZooMi 2373941 · design | Chaozhou Haizhikun E-Commerce Co. Ltd. | 21 Housewares | Pending | 2025 |
| OneOcean 2238563 | OneOcean Group Limited | 9 Electronics16 Paper35 Advertising+5 | Pending | 2022 |
| ONCEMORE 2224120 · design | an individual | 24 Textiles25 Clothing40 Treatment | Pending | 2022 |
| ONECONNECT 2179618 | Panasonic Corporation of North America | 9 Electronics42 Science | Pending | 2022 |
| OnceMore 2157428 | an individual | 24 Textiles25 Clothing | Pending | 2021 |
| ONECONNECT 2130451 · design | O'Neil Digital Solutions, LLC (a California limited liability company) | 42 Science | Pending | 2021 |