| ONEXE 2303415 · design | Taizhou Cramilo Glasses Co. Ltd. | 9 Electronics | Pending | 2024 |
| ONCE 1428559 · TMA819954 | an individual | 9 Electronics | Registered | 2012 |
| ONX 1270503 · TMA700266 · design | OnX Enterprise Solutions Ltd. | 9 Electronics42 Science | Registered | 2007 |
| ONKE 2286710 | SHANGHAI DINGYI NETWORK TECHNOLOGY CO. LTD. | 25 Clothing | Pending | 2023 |
| ONCE 2286584 | 37signals LLC | 9 Electronics | Pending | 2023 |
| ONX 2080948 | ONX, Inc. | 6 Metal19 Building37 Construction+2 | Pending | 2021 |
| ONX 1952649 | onXmaps, Inc. | 9 Electronics39 Transport42 Science | Pending | 2019 |
| ONEEQ 1948802 · TMA1200703 · design | CallisonRTKL Inc. | 35 Advertising42 Science | Registered | 2023 |
| ONZIE 1874088 · TMA1102346 | Onzie, Inc. (A corporation of California) | 25 Clothing27 Carpets28 Toys+1 | Registered | 2021 |
| OnQue 1446246 · TMA827461 | Hair Club for Men, Ltd., Inc. | 3 Cosmetics | Registered | 2012 |
| OnWEG 2360112 | Chongqing Qing Er Technology Company Limited | 11 Lighting12 Vehicles | Pending | 2024 |
| ONEXA 2334808 | GROUPE SOLMAX INC. | 1 Chemicals17 Rubber19 Building | Pending | 2024 |
| ONKUE 2207370 | Aspargo Laboratories, Inc. | 5 Pharmaceuticals | Pending | 2022 |
| ONEEKK 2266021 · TMA1285027 | Shenzhen Benbenxiang Electronic Commerce Co. Ltd. | 21 Housewares | Registered | 2025 |
| OHMNIS 2260541 · TMA1281121 · design | Ohmnis Inc. Joseph Kasumba, Blavasky Kasumba | 35 Advertising42 Science | Registered | 2025 |
| OMG 2257529 · TMA1267506 · design | OMG OASIS MEDITERRANEAN GRILL LTD. | 35 Advertising43 Restaurants | Registered | 2024 |
| Oinsi 2256199 · TMA1276183 | an individual | 14 Jewellery | Registered | 2024 |
| ONEYUS 2233734 · TMA1256667 · design | Shenzhen Aoyin Lighting Co. Ltd | 20 Furniture | Registered | 2024 |
| OMEGA 2230572 · TMA1245662 · design | an individual | 9 Electronics | Registered | 2024 |
| OMNIAGEO 2215933 · TMA1202041 | OMNIAGEO Inc. | 42 Science | Registered | 2023 |
| ONYX 2191511 · TMA1233841 | Owner not shown | 35 Advertising44 Medical | Registered | 2024 |
| OMOJI 2186481 · TMA1284476 · design | GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP. LTD. | 9 Electronics | Registered | 2025 |
| ONESIE 2186469 · TMA1223854 | Owner not shown | 12 Vehicles | Registered | 2024 |
| OWIMX 2169070 · TMA1219920 | Shenzhen Yehong Electronic Commerce Co. Ltd. | 21 Housewares | Registered | 2024 |
| ONCAI 2157827 · TMA1218367 · design | Shenzhen Yichen Shidai Trading Co. Ltd. | 25 Clothing | Registered | 2024 |