| OfficeOn 2373237 | Robert Bosch Power Tools GmbH | 9 Electronics35 Advertising36 Finance+2 | Pending | 2024 |
| OfficeOn 2231875 | Robert Bosch Power Tools GmbH | 9 Electronics | Pending | 2022 |
| OFFICINA 1646915 · TMA926439 | Monotype ITC Inc. | 9 Electronics16 Paper | Registered | 2016 |
| OVISON 1816213 · TMA1040336 | an individual | 5 Pharmaceuticals | Registered | 2019 |
| OFEZUMIR 2255895 · TMA1274666 | Incyte Holdings Corporation | 5 Pharmaceuticals16 Paper44 Medical | Registered | 2024 |
| OPSIN 2182254 · TMA1212557 | SiOnyx, LLC | 9 Electronics | Registered | 2023 |
| OPZIMRUS 2141814 · TMA1155569 | Coherus Biosciences, Inc. | 5 Pharmaceuticals | Registered | 2022 |
| Opigno 2111720 · TMA1277264 | an individual | 9 Electronics41 Education42 Science | Registered | 2024 |
| OBICUM 2100300 · TMA1200043 | an individual | 25 Clothing | Registered | 2023 |
| OPQSMIL 2065640 · TMA1173333 | an individual | 25 Clothing | Registered | 2023 |
| OVCINDEN 2057204 · TMA1169800 | Owner not shown | 5 Pharmaceuticals | Registered | 2023 |
| oopsmark 1951225 · TMA1234140 | an individual | 12 Vehicles14 Jewellery18 Leather | Registered | 2024 |
| OPSGENIE 1949280 · TMA1266151 | OpsGenie, Inc. | 9 Electronics42 Science | Registered | 2024 |
| OVOSENSE 1855350 · TMA1046432 | an individual | 7 Machines9 Electronics | Registered | 2019 |
| OPSYNVI 1847980 · TMA1074358 | Actelion Pharmaceuticals Ltd. | 5 Pharmaceuticals | Registered | 2020 |
| OPSCENTRAL 1809804 · TMA1005202 | AppDynamics, Inc. | 9 Electronics37 Construction41 Education+1 | Registered | 2018 |
| OBICMI 1792237 · TMA1035136 | an individual | 5 Pharmaceuticals | Registered | 2019 |
| OVIXAN 1781846 · TMA1004252 | an individual | 5 Pharmaceuticals | Registered | 2018 |
| OPSMATRIX 1747288 · TMA948593 | Intouch Insight Inc. | 9 Electronics35 Advertising42 Science | Registered | 2016 |
| OPSUMIT 1737740 · TMA945234 · design | Actelion Pharmaceuticals Ltd. | 5 Pharmaceuticals | Registered | 2016 |
| OVCN 1736818 · TMA944032 | Ontario Volunteer Centre Network, a lawful association | 35 Advertising36 Finance41 Education+1 | Registered | 2016 |
| OffiSmart 1730550 · TMA965357 | Avandium Trading Ltd. | 2 Paints8 Hand9 Electronics+3 | Registered | 2017 |
| OVASCIENCE 1726248 · TMA936691 | OvaScience, Inc. | 44 Medical | Registered | 2016 |
| oppscan 1619827 · TMA924793 | an individual | 9 Electronics | Registered | 2016 |
| OPPOSOME 1572294 · TMA856905 | ORX PHARMACEUTICAL CORPORATION | 5 Pharmaceuticals42 Science44 Medical | Registered | 2013 |