| OMNIPOST 0705486 · TMA430972 | CANADA POST CORPORATION | 9 Electronics | Registered | 1994 |
| OMNIPOST 0702723 · TMA412683 | CANADA POST CORPORATION | 38 Telecommunications39 Transport40 Treatment | Registered | 1993 |
| OnPOZ 2259531 | 14677293 Canada Inc. | 9 Electronics42 Science | Pending | 2023 |
| OmniPOS 2061097 · TMA1219620 | an individual | 9 Electronics35 Advertising36 Finance+2 | Registered | 2024 |
| ONEPASS 1625677 · TMA895725 · design | BISSELL Inc. | 7 Machines | Registered | 2015 |
| OnePass 1582434 · TMA845884 | Stanley Black & Decker, Inc. | 9 Electronics | Registered | 2013 |
| ONEPASS 1516389 · TMA817660 | Degelman Industries LP, by its general partner, Degelman Industries GP Inc. | 7 Machines | Registered | 2012 |
| ONEPASS 1157157 · TMA626961 | Danby Technologies Corporation | 9 Electronics16 Paper35 Advertising+2 | Registered | 2004 |
| ONEPASS 0837844 · TMA492063 | UNITED AIRLINES, INC. | 39 Transport | Registered | 1998 |
| ONEPUSH 2336600 | an individual | 19 Building27 Carpets45 Legal | Pending | 2024 |
| ONEVEST 2142895 · design | One Wealth Technologies Inc. | 9 Electronics36 Finance45 Legal | Pending | 2021 |
| OneVest 2135941 | One Wealth Technologies Inc. | 9 Electronics36 Finance45 Legal | Pending | 2021 |
| OMIEBOX 2244341 · TMA1258468 | OmieLife, Inc. | 21 Housewares | Registered | 2024 |
| ONUPGO 2212812 · TMA1243170 · design | Shenzhen Weigeer Trading Co., Ltd. | 25 Clothing | Registered | 2024 |
| OMVOS 2183393 · TMA1278877 | OMVOS INC. | 12 Vehicles | Registered | 2024 |
| ONEPAGER 2177669 · TMA1215516 | Chronicle Graphics, Inc. | 9 Electronics | Registered | 2023 |
| OMNIVISION 2177450 · TMA1284411 | OmniVision Technologies, Inc. | 9 Electronics10 Medical35 Advertising | Registered | 2025 |
| OneBox 2167250 · TMA1206593 | Owner not shown | 9 Electronics | Registered | 2023 |
| ONVIZLI 2160304 · TMA1201862 | an individual | 5 Pharmaceuticals | Registered | 2023 |
| ONVAXYG 2149659 · TMA1189865 | GLAXO GROUP LIMITED | 5 Pharmaceuticals | Registered | 2023 |
| OMPECO 2138291 · TMA1179520 | an individual | 7 Machines | Registered | 2023 |
| Omnpak 2109460 · TMA1225856 | SWISS ARMY KNIFE LIMITED | 9 Electronics18 Leather | Registered | 2024 |
| OMNIPHASE 2090964 · TMA1181600 | Omniphase, Inc. | 9 Electronics42 Science | Registered | 2023 |
| ONPACK 2074492 · TMA1208269 | ORIHIRO CO. LTD. | 7 Machines | Registered | 2023 |
| ONIBEGIE 2004398 · TMA1211569 · design | KOMATSU MATERE Co. Ltd. | 18 Leather24 Textiles25 Clothing | Registered | 2023 |