| O'Grady Peyton International | $72,800 | 28 |
| O'Melveny & Myers | $225,000 | 13 |
| O'Reilly Technology Services | $160,000 | 13 |
| O.C. Tanner Company | $129,246 | 14 |
| O2 Technologies | $98,750 | 16 |
| O3 Technology Solutions | $105,300 | 72 |
| o9 Solutions | $132,664 | 111 |
| Oak Hill Advisors | $150,000 | 12 |
| Oak River Insurance Company | $158,000 | 10 |
| Oak Street Health MSO | $143,507 | 34 |
| Oakland University | $45,000 | 41 |
| Oakston Technologies | $107,988 | 10 |
| Oakton Technologies | $105,997 | 34 |
| Oakwood Healthcare | $71,577 | 15 |
| Oasis Professional Management Group | $70,720 | 37 |
| Oasys Technologies | $103,605 | 19 |
| Obayashi | $92,400 | 29 |
| Obentech Consulting | $84,000 | 13 |
| Oberlin College | $65,000 | 27 |
| Oberon IT | $100,000 | 23 |
| Object Data | $124,000 | 19 |
| Object Technology Solutions | $96,000 | 16 |
| Objects On Net | $105,300 | 38 |
| Objectways Technologies | $112,528 | 13 |
| ObjectWin Technology | $113,942 | 13 |
| OC&C Strategy Consultants | $117,000 | 17 |
| Occidental Petroleum | $157,900 | 50 |
| Ocean Avenue Veterinary Hospital | $200,000 | 13 |
| Ocean Blue Solutions | $113,000 | 20 |
| Ocher Technology Group | $105,227 | 25 |
| Ochsner Clinic Foundation | $69,420 | 226 |
| Oclc | $123,600 | 49 |
| Octagon IT | $95,247 | 44 |
| Octagos Health | $92,979 | 10 |
| Octahedron | $97,300 | 11 |
| Octane Lending | $185,662 | 15 |
| Octans Group | $90,000 | 15 |
| Octans | $110,802 | 10 |
| Octus Intelligence | $141,250 | 10 |
| Ocular Therapeutix | $140,000 | 10 |
| Oculii | $94,765 | 19 |
| Odessa Junior College | $64,397 | 11 |
| Odessa Technologies | $132,868 | 10 |
| Odin Aerotech | $108,097 | 12 |
| Odoo | $118,000 | 41 |
| ODP International | $110,947 | 21 |
| Odyssey Reinsurance Company | $169,600 | 10 |
| Oec Freight (Ny) | $78,998 | 11 |
| Ofinno | $160,000 | 13 |
| Ohio Conference Of Seventh-Day Adventists | $63,580 | 11 |
| Ohio Farmers Insurance Company | $109,079 | 40 |
| Ohio State Dental Faculty Practice | $176,010 | 10 |
| OhioHealth | $71,926 | 89 |
| OhioHealth Physician Group | $325,000 | 21 |
| Ojus | $105,010 | 14 |
| OKBL USA Technology | $200,796 | 81 |
| OKC USA Holding | $211,440 | 18 |
| Oklahoma Blood Institute | $71,000 | 16 |
| Oklahoma Medical Research Foundation | $56,202 | 21 |
| Oklahoma State University | $77,845 | 108 |
| Okta | $163,777 | 209 |
| Olam Americas | $300,019 | 19 |
| Old Dominion University | $84,048 | 121 |
| Oliver Wyman Actuarial Consulting | $125,125 | 19 |
| Oliver Wyman | $240,000 | 31 |
| Olivet Academy | $52,416 | 13 |
| Olivet University | $73,440 | 25 |
| Olsson | $83,800 | 21 |
| Olympus Corporation of the Americas | $110,708 | 12 |
| OM Partners | $98,000 | 71 |
| Om Tek | $106,000 | 47 |
| Omada Health | $183,444 | 10 |
| Omaha Public Power District | $132,421 | 11 |
| Omaha Public Schools, District 0001 | $82,107 | 13 |
| Omd | $97,000 | 53 |
| Omni Family Health | $280,000 | 11 |
| OMNI Health Services | $50,000 | 37 |
| Omnicell | $140,267 | 37 |
| Omnicron Technologies | $84,095 | 16 |
| Omnissa | $181,862 | 118 |
| OmniVision Technologies | $124,197 | 97 |
| Omron Robotics and Safety Technologies | $134,067 | 22 |
| Omsai Com | $93,771 | 10 |
| Oncorre | $109,564 | 36 |
| One Algorithm | $100,000 | 13 |
| One on One Physical Therapy | $78,790 | 34 |
| OneH2 | $80,000 | 28 |
| Onelink Solution | $98,041 | 10 |
| OneMain General Services | $96,429 | 172 |
| ONEOK Services Company | $92,019 | 11 |
| Onestopd Solutions | $105,976 | 23 |
| OneSubsea | $86,190 | 11 |
| OneTek Software Solutions | $91,100 | 15 |
| ONEUS Technologies | $80,600 | 55 |
| Onix Networking | $120,000 | 46 |
| Only It Consulting | $98,010 | 48 |
| Ontario-Montclair School District | $70,710 | 11 |
| Ontex Operations | $114,915 | 11 |
| Onto Innovation | $133,000 | 39 |
| Onward Robotics (f/k/a IAM ROBOTICS, INC.) | $97,000 | 11 |
| Onward Technologies | $87,423 | 52 |
| Ooma | $185,000 | 10 |
| Opel Systems | $97,032 | 10 |
| Opelsoft | $90,480 | 29 |
| Open Access Technology International | $108,368 | 20 |
| Open Avenues Foundation | $88,005 | 204 |
| Open Philanthropy Project | $124,604 | 12 |
| Open Systems International | $113,047 | 34 |
| Open Systems | $97,365 | 25 |
| Open Text | $149,134 | 20 |
| OpenAI OpCo | $270,000 | 311 |
| OpenBox Solutions | $92,331 | 15 |
| Opendoor Labs | $212,000 | 15 |
| OpenGov | $122,970 | 31 |
| openkyber | $105,737 | 12 |
| OpenTable | $194,928 | 20 |
| OpenTeQ Technologies | $111,561 | 16 |
| Operation Technology | $111,072 | 18 |
| Opinr | $90,000 | 10 |
| OPmobility Holding | $100,650 | 12 |
| Oportun | $156,546 | 38 |
| Opportunity Financial | $103,080 | 11 |
| Opportunity IT Solutions | $84,094 | 12 |
| Optigrid | $155,709 | 10 |
| Optimal Technologies | $96,564 | 46 |
| optimal | $85,571 | 27 |
| Optime-Tech | $100,714 | 13 |
| Optimized Investment Holdings | $123,600 | 30 |
| Optimum Care Services | $62,400 | 12 |
| Optimum Media | $103,099 | 11 |
| Optimus Services | $83,720 | 25 |
| Optimus Unit | $90,095 | 14 |
| Optivent Group | $105,997 | 39 |
| Optiver Services | $175,000 | 59 |
| Optomi | $145,600 | 14 |
| Optum | $125,798 | 996 |
| Optym | $130,500 | 25 |
| Opulentsoft | $108,077 | 19 |
| Opus Technologies | $131,000 | 33 |
| Opusclip | $175,000 | 16 |
| Ora Apps | $100,756 | 18 |
| Orabase Solutions | $92,955 | 38 |
| Oracle | $143,062 | 2,111 |
| Oral Roberts University | $64,771 | 16 |
| Orangeburg County School District | $62,689 | 73 |
| Orangepeople | $122,294 | 10 |
| Orasys | $114,400 | 22 |
| Orbisiq | $100,797 | 22 |
| Orbit Systems | $105,000 | 20 |
| Oregon Health & Science University | $93,057 | 204 |
| Oregon Institute of Technology | $76,000 | 15 |
| Oregon State University | $70,008 | 212 |
| OReilly Technology Services | $145,950 | 13 |
| Oremda Infotech | $93,164 | 16 |
| Orien Solutions | $103,917 | 75 |
| Oriental Trading Company | $105,000 | 11 |
| Origence | $145,000 | 13 |
| Origin Hubs | $91,050 | 51 |
| Origintek Solutions | $101,327 | 32 |
| Orion Systems Integrators | $123,656 | 191 |
| Oriontek | $103,314 | 48 |
| Orison Solutions | $100,870 | 12 |
| Orlando Health | $92,040 | 18 |
| Orlando Health Medical Group | $400,000 | 17 |
| Orna Therapeutics | $131,611 | 12 |
| Orpheus Academy of Music | $42,400 | 10 |
| Orpine | $106,000 | 129 |
| Orrba Systems | $92,841 | 38 |
| Orrick, Herrington & Sutcliffe | $212,826 | 17 |
| Orsted North America | $130,000 | 23 |
| Osa Operations | $114,122 | 10 |
| Oscar Management | $178,200 | 33 |
| Oscar Renda Contracting | $89,441 | 16 |
| Oscilar | $210,000 | 12 |
| OSF Healthcare System | $73,567 | 117 |
| OSF Multi-Specialty Group | $303,000 | 110 |
| OSI Digital | $124,000 | 37 |
| Osi Engineering | $133,380 | 20 |
| OSIsoft | $151,975 | 24 |
| Osmose Utilities Services | $80,340 | 12 |
| Oss | $78,000 | 43 |
| OT Technology | $151,000 | 74 |
| Otis Elevator Company | $126,339 | 39 |
| Otis It | $110,000 | 17 |
| Otis Technology | $79,020 | 12 |
| Otsuka America Pharmaceutical | $185,497 | 14 |
| Otsuka Pharmaceutical Development & Commercialization | $175,000 | 19 |
| Otter.ai | $188,000 | 56 |
| OU Health Partners | $360,165 | 56 |
| Our Lady of Lourdes Memorial Hospital, Inc. d/b/a Guthrie Lourdes Hospital | $525,000 | 11 |
| Our Next Energy | $115,251 | 10 |
| OuraRing | $182,000 | 17 |
| Ouro Global | $150,355 | 26 |
| Ouster | $153,536 | 16 |
| Outdoor Wireless Networks | $123,739 | 23 |
| Outpace | $84,094 | 16 |
| Outreach | $178,500 | 16 |
| Outreach Manual Physical Therapy | $62,000 | 10 |
| Outreach Physical and Occupational Therapy and Speech Rehabilitation, PLLC | $103,500 | 16 |
| Overhaul Group | $95,119 | 12 |
| Overhead Door | $120,494 | 29 |
| Overjet | $212,000 | 14 |
| Ovs Technologies | $111,072 | 39 |
| Owens & Minor Distribution | $101,177 | 13 |
| Owens & Minor Medical | $136,046 | 10 |
| Owens Corning Corporate Services | $129,792 | 24 |
| Oxfam-America | $91,890 | 10 |
| Ozarks Medical Center | $318,250 | 13 |