| OTHA 2106260 · TMA1176627 | 6594409 canada inc | 9 Electronics | Registered | 2023 |
| OTTO 2041077 · TMA1142839 · design | Owner not shown | 8 Hand | Registered | 2022 |
| OTTO 1915264 · TMA1094996 | Fastenhaus Limited | 5 Pharmaceuticals9 Electronics11 Lighting+7 | Registered | 2021 |
| OTTO 1903080 · TMA1083703 · design | Otto International, Inc. a legal entity | 18 Leather25 Clothing | Registered | 2020 |
| OTTO 1893325 · TMA1077910 | Otto International, Inc. a legal entity | 18 Leather25 Clothing | Registered | 2020 |
| OTTO 1835669 · TMA1011576 · design | Persen Technologies Inc. | 9 Electronics38 Telecommunications39 Transport+1 | Registered | 2018 |
| OTTO 1785320 · TMA1055778 | an individual | 6 Metal20 Furniture21 Housewares | Registered | 2019 |
| OTTO 1779783 · TMA1055784 · design | an individual | 6 Metal20 Furniture | Registered | 2019 |
| OTTO 1746576 · TMA987861 | CLEARPATH ROBOTICS, INC. | 7 Machines35 Advertising42 Science | Registered | 2018 |
| OTT 1403846 · TMA746885 | D. Jenner OTT Legal Franchise Corp. | 45 Legal | Registered | 2009 |
| OTTO 1270777 · TMA700579 · design | Otto International, Inc. | 25 Clothing | Registered | 2007 |
| OTTO 1269324 · TMA677201 · design | Persen Technologies Inc. | 9 Electronics | Registered | 2006 |
| OTTÓ 2324871 | FUTUREVERSE CORPORATION LIMITED | 9 Electronics35 Advertising36 Finance+2 | Pending | 2024 |
| OTTO 2301369 · design | OTTOGI CORPORATION, a legal entity | 29 Meat30 Coffee | Pending | 2023 |
| OTTO 2266409 · design | Owner not listed | 7 Machines11 Lighting21 Housewares | Pending | 2023 |
| OTTO 2182180 | Shapeways, Inc. | 42 Science | Pending | 2022 |
| OTT 2167702 | OTT FINANCIAL GROUP CORPORATION | 9 Electronics35 Advertising36 Finance+2 | Pending | 2022 |
| OTTO 2157976 · design | Otto Studio Inc. | 27 Carpets35 Advertising | Pending | 2022 |
| OTTO 2110696 | TMGCore, LLC | 9 Electronics | Pending | 2021 |
| OTA 2110222 | ONTARIO TRUCKING ASSOCIATION | 9 Electronics16 Paper35 Advertising+3 | Pending | 2021 |
| OTTAWA 1683547 · TMA933489 · design | OTTAWA MACDONALD-CARTIER INTERNATIONAL AIRPORT AUTHORITY / L'ADMINISTRATION DE L'AÉROPORT INTERNATIONAL MACDONALD-CARTIER D'OTTAWA | 35 Advertising36 Finance39 Transport | Registered | 2016 |
| OTTAWA 0847598 · TMA494186 · design | OTTAWA TOURISM AND CONVENTION AUTHORITY INC. | 9 Electronics14 Jewellery16 Paper+6 | Registered | 1998 |
| OTTAWA 2320535 · design | OTTAWA TOURISM AND CONVENTION AUTHORITY, INC./L'ADMINISTRATION DU TOURISME ET DES CONGRES D'OTTAWA, INC. | 9 Electronics14 Jewellery16 Paper+7 | Pending | 2024 |
| OTTAWA 0912789 · design | OTTAWA TRANSITION BOARD | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2001 |
| OTTAWA 0912787 · design | OTTAWA TRANSITION BOARD | 1 Chemicals2 Paints3 Cosmetics+42 | Pending | 2001 |