| TAThe Argen Corporation | San Diego | CA | Fabricated Metal Product Manufacturing332999 | — | ◇ UNVERIFIED |
| TBThe Box Company INC | San Diego | CA | Paper Manufacturing322212 | — | ◇ UNVERIFIED |
| TCThe City of San Diego | San Diego | CA | Transportation Equipment Manufacturing336350 | — | ◇ UNVERIFIED |
| TCThe City of San Diego | San Diego | CA | Nonmetallic Mineral Product Manufacturing327999 | — | ◇ UNVERIFIED |
| THThe Hyperspace Lighting Company Limited Liability Company | San Diego | CA | Electrical Equipment, Appliance & Component Manufacturing335131 | — | ◇ UNVERIFIED |
| THThe Hyperspace Lighting Company Limited Liability Company | San Diego | CA | Electrical Equipment, Appliance & Component Manufacturing335131 | — | ◇ UNVERIFIED |
| THThe Hyperspace Lighting Company Limited Liability Company | San Diego | CA | Electrical Equipment, Appliance & Component Manufacturing335129 | — | ◇ UNVERIFIED |
| TMThe Mahogany Shop | San Diego | CA | Chemical Manufacturing325510 | — | ◇ UNVERIFIED |
| TQThe Quikrete Companies | San Diego | CA | Nonmetallic Mineral Product Manufacturing327331 | — | ◇ UNVERIFIED |
| TRThermofisher Rsd | San Diego | CA | Computer and Electronic Product Manufacturing334516 | — | ◇ UNVERIFIED |
| TFThermo Fisher Scientific Rds | San Diego | CA | Plastics and Rubber Products Manufacturing326199 | — | ◇ UNVERIFIED |
| TIThermopeutix INC | San Diego | CA | Miscellaneous Manufacturing339112 | — | ◇ UNVERIFIED |
| TMThree Man Corporation | San Diego | CA | Printing and Related Support Activities323111 | — | ◇ UNVERIFIED |
| TBThunder Boats Unlimited INC | San Diego | CA | Transportation Equipment Manufacturing336612 | — | ◇ UNVERIFIED |
| TETitan Electronics | San Diego | CA | Computer and Electronic Product Manufacturing334412 | — | ◇ UNVERIFIED |
| TMTlc Medical Transport LLC | San Diego | CA | Petroleum and Coal Products Manufacturing324191 | — | ◇ UNVERIFIED |
| TITocagen INC | San Diego | CA | Chemical Manufacturing325414 | — | ◇ UNVERIFIED |
| TITocagen INC | San Diego | CA | Chemical Manufacturing325414 | — | ◇ UNVERIFIED |
| TTogronis | San Diego | CA | Food Manufacturing311999 | — | ◇ UNVERIFIED |
| TBTop Brands Distribution INC | San Diego | CA | Food Manufacturing311412 | — | ◇ UNVERIFIED |
| TBTop Brands Distribution Oasis Naturals | San Diego | CA | Food Manufacturing311999 | — | ◇ UNVERIFIED |
| TLTortilleria La Princesa | San Diego | CA | Food Manufacturing311830 | — | ◇ UNVERIFIED |
| THTraditions Health | San Diego | CA | Paper Manufacturing322219 | — | ◇ UNVERIFIED |
| TTTrefoil Therapeutics INC | San Diego | CA | Chemical Manufacturing325412 | — | ◇ UNVERIFIED |
| TBTrilink Biotechnologies | San Diego | CA | Chemical Manufacturing325998 | — | ◇ UNVERIFIED |
| TBTrutino Biosciences | San Diego | CA | Chemical Manufacturing325412 | — | ◇ UNVERIFIED |
| THTungsten Heavy Powder, Inc., Dba: Tungsten Heavy Powder and Parts | San Diego | CA | Machinery Manufacturing333415 | — | ◇ UNVERIFIED |
| TPTurning Point Therapeutics | San Diego | CA | Chemical Manufacturing325412 | — | ◇ UNVERIFIED |
| TKTurn Key Solutions | San Diego | CA | Transportation Equipment Manufacturing336611 | — | ◇ UNVERIFIED |
Unchained Labs | San Diego | CA | Computer and Electronic Product Manufacturing334516 | — | ◇ UNVERIFIED |
| UIUnigrid INC | San Diego | CA | Electrical Equipment, Appliance & Component Manufacturing335910 | — | ◇ UNVERIFIED |
| UEUnion Electric Motor Service | San Diego | CA | Electrical Equipment, Appliance & Component Manufacturing335312 | — | ◇ UNVERIFIED |
| UCUnited Cerebral Palsy/ready Stamps | San Diego | CA | Miscellaneous Manufacturing339943 | — | ◇ UNVERIFIED |
| UMUpgrade Marine | San Diego | CA | Transportation Equipment Manufacturing336611 | — | ◇ UNVERIFIED |
| UMUrethane Masters INC | San Diego | CA | Plastics and Rubber Products Manufacturing326150 | — | ◇ UNVERIFIED |
| UCUS Coast Guard Air Station | San Diego | CA | Machinery Manufacturing333611 | — | ◇ UNVERIFIED |
| URUsmc Recruit Depot | San Diego | CA | Transportation Equipment Manufacturing336992 | — | ◇ UNVERIFIED |
| UNUS Navy Public Works Center | San Diego | CA | Transportation Equipment Manufacturing336414 | — | ◇ UNVERIFIED |
| USUsn Southwest Federal Fire Dept | San Diego | CA | Transportation Equipment Manufacturing336611 | — | ◇ UNVERIFIED |
| UAUss Annapolis - Cal. Marine | San Diego | CA | Fabricated Metal Product Manufacturing332410 | — | ◇ UNVERIFIED |
| UBUss Boxer Lhd 4 | San Diego | CA | Transportation Equipment Manufacturing336611 | — | ◇ UNVERIFIED |
| UCUwv-3511 Cdrs, LLC | San Diego | CA | Machinery Manufacturing333921 | — | ◇ UNVERIFIED |
| VPValerio's Pilipino Bake Shop Inc. | San Diego | CA | Food Manufacturing311811 | — | ◇ UNVERIFIED |
| VPValterra Products LLC | San Diego | CA | Transportation Equipment Manufacturing336612 | — | ◇ UNVERIFIED |
| VSVanguard Space Technologies | San Diego | CA | Transportation Equipment Manufacturing336419 | — | ◇ UNVERIFIED |
| VSVanguard Space Technologies INC | San Diego | CA | Computer and Electronic Product Manufacturing334220 | — | ◇ UNVERIFIED |
| VMVarian Medical Systems | San Diego | CA | Computer and Electronic Product Manufacturing334517 | — | ◇ UNVERIFIED |
| VSVa San Diego Healthcare System | San Diego | CA | Nonmetallic Mineral Product Manufacturing327999 | — | ◇ UNVERIFIED |
| VEVas Engineering INC | San Diego | CA | Computer and Electronic Product Manufacturing334412 | — | ◇ UNVERIFIED |
| VDVenture Dynamics, INC. | San Diego | CA | Transportation Equipment Manufacturing336611 | — | ◇ UNVERIFIED |