| OPENSPORT 2101702 · TMA1173887 | SHOKZ (SINGAPORE) PTE. LTD. | 9 Electronics | Registered | 2023 |
| OPENSHIFT 1711741 · TMA987980 | Red Hat, Inc. | 9 Electronics42 Science | Registered | 2018 |
| OPENSPARC 1304573 · TMA837815 | SPARC INTERNATIONAL, INC. | 9 Electronics16 Paper | Registered | 2012 |
| OpenSPR 2315273 | Nicoya Lifesciences, Inc. | 1 Chemicals42 Science | Pending | 2024 |
| OpenSPR 2015127 | Nicoya Lifesciences, Inc. | 9 Electronics | Pending | 2020 |
| OPENSOLARIS 1253288 · TMA794683 | Oracle America, Inc. | 7 Machines9 Electronics41 Education+1 | Registered | 2011 |
| openspeed 2132262 · TMA1232141 | SHOKZ (SINGAPORE) PTE. LTD. | 9 Electronics | Registered | 2024 |
| openswim 2056371 · TMA1198550 | SHOKZ (SINGAPORE) PTE. LTD. | 9 Electronics | Registered | 2023 |
| opensrci 1990414 · TMA1126966 | an individual | 36 Finance | Registered | 2022 |
| OPENSCOPIC 1822131 · TMA1018840 | Richard S. Boorman Professional Corporation | 44 Medical | Registered | 2019 |
| OPENSURE 1771418 · TMA1032251 | Boston Scientific Scimed, Inc. | 10 Medical | Registered | 2019 |
| OPENSPACE 1702991 · TMA928586 | LOGIX ITS INC. | 9 Electronics19 Building | Registered | 2016 |
| OPENSHARE 1609719 · TMA893368 | ONCARD MARKETING, INC. DBA REVTRAX | 35 Advertising42 Science | Registered | 2015 |
| OPENSET 1393974 · TMA755566 | Owner not shown | 9 Electronics | Registered | 2009 |
| OPENSUMI 2235367 | Owner not listed | 9 Electronics42 Science | Pending | 2021 |
| OPENSERGO 2192648 | Alibaba Cloud (Singapore) Private Limited | 9 Electronics42 Science | Pending | 2022 |
| OPENSTORE 2133136 | Miami Labs, Inc. | 9 Electronics35 Advertising36 Finance+1 | Pending | 2021 |
| OPENSEARCH 2133027 | Amazon Technologies, Inc. | 9 Electronics42 Science | Pending | 2021 |
| OPENSENTIENT 2297103 | SENTIENT MACHINE HOLDINGS CORPORATION, operating through its division OPENSENTIENT INSTITUTE | 42 Science | Pending | 2023 |
| OPENCLINICA 1457286 · TMA778374 | Akaza Research LLC | 9 Electronics41 Education42 Science | Registered | 2010 |
| OFFNIC 2237540 · TMA1258203 | Owner not listed | 25 Clothing34 Tobacco | Registered | 2024 |
| OFVENS 2236210 · TMA1256871 | Heyuan Youzhuoke Electronic Commerce Co. Ltd | 20 Furniture | Registered | 2024 |
| OUFANG 2208798 · TMA1252404 · design | Nanjing Oufang Textile Co. Ltd. | 24 Textiles25 Clothing | Registered | 2024 |
| OBONES 2199146 · TMA1284540 | an individual | 9 Electronics | Registered | 2025 |
| OVNS 2181020 · TMA1229051 | OVNS (Shenzhen) Technology Co. Ltd. | 34 Tobacco | Registered | 2024 |