| Offshore Development Center | New York |
| Offshorly | |
| OffspringNet | Colorado |
| Ofice Imaging Solutions, Inc. | Arkansas |
| Ofinno | |
| Ofni Systems, Inc. | North Carolina |
| OFS Fitel, LLC | Georgia |
| OFS-Portal, LLC | Texas |
| Ofspace, LLC | |
| OG Technologies | |
| Ogden Area Linux Users' Group | Utah |
| Ogden Communications, Inc. | Michigan |
| Ogden-Weber Technical College | Utah |
| Ogdenian | New York |
| OGDIR Technologies, LLC | New Jersey |
| Ogee Studio, Inc. | California |
| Ogeechee Technical College | Georgia |
| Oglala Lakota College Department of Math, Science and Technology | South Dakota |
| Ogle Design, Inc. | |
| Ogma, Inc. | |
| Ogrelogic | |
| OH Partners | |
| OH Pharmaceutical | |
| Oh, Hello Design Co. | |
| Ohanae, Inc. | New York |
| Ohio Academic Resources Network | Ohio |
| Ohio Aerospace Institute | |
| Ohio Automation Schematic and PCB Software | Ohio |
| Ohio Automation, Inc. | Ohio |
| Ohio Business College | Ohio |
| Ohio Cancer Research | |
| Ohio Christian University | Ohio |
| Ohio Distinctive | Ohio |
| Ohio Dominican University | Ohio |
| Ohio Northern University Computer Science Bachelor's Degree | Ohio |
| Ohio Northern University Mathematics Degree Program | Ohio |
| Ohio State University Center for Quantum Information Science and Engineering | Ohio |
| Ohio State University Department of Computer Science and Engineering | Ohio |
| Ohio State University Department of Electrical and Compute Engineering | Ohio |
| Ohio State University Department of Mathematics | Ohio |
| Ohio State University Fisher College of Business | Ohio |
| Ohio Supercomputer Center | Ohio |
| Ohio Technical College | Ohio |
| Ohio Technology Consortium | Ohio |
| Ohio Telecom Association | Ohio |
| Ohio University Mathematics Department | Ohio |
| Ohio University School of Electrical Engineering and Computer Science | Ohio |
| Ohio Web Pro Design, LLC | Ohio |
| Ohio Web Technologies | Ohio |
| Ohio Welesyan University | Ohio |