| OSDev.org | Texas |
| Oseberg | |
| Osel, Inc. | California |
| OSGeo | |
| OSH Park, LLC | |
| Oshyn, Inc. | California |
| Osigu | |
| Osiris Software | Oklahoma |
| Osirys Computer Systems, LLC | Wyoming |
| OSIsoft | California |
| OSK Technology, Inc. | Pennsylvania |
| Oska Wellness | California |
| Osky Blue | |
| OSLA Agency | |
| Osmol Therapeutics | |
| OSMOS | |
| Osmoses | |
| OsmosisAI, Inc. | Texas |
| OSnews | Utah |
| OSNovative Systems | California |
| OSO Grande Technologies, Inc. | New Mexico |
| Oso Security, Inc. | New York |
| Oso Semiconductor | |
| OSOLabs, LLC | California |
| OSoLiS, LLC | New York |
| OSoSLO | California |
| OSP | Texas |
| Osprey Medical, Inc. | Minnesota |
| Osprey Retail Systems, Inc. | Massachusetts |
| Osprey Software | |
| OspreyBioscience | |
| OspreyData, Inc. | California |
| OSR Open Systems Resources, Inc. | New Hampshire |
| OSS Insight | California |
| OSS Nokalva, Inc. | New Jersey |
| Osseus | Texas |
| OSSI | Nevada |
| Ossia Systems | Illinois |
| OSSIO, Inc. | Massachusetts |
| Ossisto | California |
| Ossium Health, Inc. | California |
| OST, Inc. | District of Columbia |
| Ostari, Inc. | California |
| Osteal Therapeutics, Inc. | |
| Ostendio, Inc. | |
| Ostendo Technologies, Inc. | |
| Ostentus Therapeutics, Inc. | |
| Osteoboost Health, Inc. | |
| OsteoCentric Technologies | |
| Osteonovus | Ohio |