| Comtech Plus Low Voltage Company | Ryuya Ishizuka | — | (310) 527 1493 | Other | Garden Grove · Orange County | — | — |
| Con-cept Painting | Valadez Sergio Aguilar | — | (949) 466 0499 | Windows, patio, painters | Tustin · Orange County | — | — |
| Conam Building Co | Nicholas Robert Lutz | — | (949) 498 1003 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Conc Advantage INC | Bruce Martin Williams | info@concadvantage.com | (949) 557 1204 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Concept 2 Reality Construction | Shane Earl Reyna | — | (949) 637 2564 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Concept Air | Concept Air | — | (714) 294 3711 | HVAC | Anaheim · Orange County | — | — |
| Concept Construction | Casey Herbert Hilgenberg | — | (714) 514 0363 | GC, remodel, ADU | Placentia · Orange County | — | — |
| Concept Construction Group | Mehdi Momen | — | (949) 299 7261 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Concept One Homes INC | Scott Neal Hess | — | (714) 390 8323 | GC, remodel, ADU | Laguna Niguel · Orange County | — | — |
| Concept Paving Solutions INC | Joshua Ty Cobb | — | (714) 997 2200 | Other | Mission Viejo · Orange County | — | — |
| Concepts Decorating Solutions INC | Juan Antonio Ruiz Mendez | — | (714) 404 6888 | Windows, patio, painters | Tustin · Orange County | — | — |
| Concierge Pavers And Synthetic Turf | Concierge Pavers And Synthetic Turf | — | (949) 606 5191 | Other | Coto De Caza · Orange County | — | — |
| Concordia Construction INC | Martin Leandro Echezarreta | — | (562) 440 7293 | Electricians | Mission Viejo · Orange County | — | — |
| Concrete Cleaning & Coating INC | James Richard Wentz | — | (714) 841 0554 | Other | Huntington Beach · Orange County | — | — |
| Concrete Concepts | Concrete Concepts | — | (949) 400 6639 | Other | Newport Beach · Orange County | — | — |
| Concrete Construction Corporation | Salvatore Michael Rizzuto | — | (562) 694 0420 | Other | La Habra · Orange County | — | — |
| Concrete Creations Coatings | Concrete Creations Coatings | — | (949) 394 4941 | Other | Tustin · Orange County | — | — |
| Concrete Creations Restoration | Camille Gabriela Lopez | — | (949) 403 9665 | Restoration | Yorba Linda · Orange County | — | — |
| Concrete Doctor Restoration | Concrete Doctor Restoration | — | (949) 842 3583 | Restoration | Dana Point · Orange County | — | — |
| Concrete Hazard Solutions INC | Brian Ronald Fischbeck | — | (714) 292 6150 | Other | Santa Ana · Orange County | — | — |
| Concrete Master | Concrete Master | — | (949) 235 8968 | Other | Lake Forest · Orange County | — | — |
| Concrete Outlaws | Perez Rodolfo Sandoval | — | (714) 333 1490 | Other | Yorba Linda · Orange County | — | — |
| Concrete Placement INC | Marla Gaye Fleming | — | (877) 586 5678 | Other | Tustin · Orange County | — | — |
| Concrete Polishing Dynasty | Herrera Giovanni Dominguez | — | (714) 553 9077 | Other | Fountain Valley · Orange County | — | — |
| Concrete Pro | Polonia Faye Pousima | — | (714) 561 4455 | Other | Fullerton · Orange County | — | — |
| Concrete Pumping INC | Collin Lynn Fleming | — | (877) 586 5678 | Other | Tustin · Orange County | — | — |
| Concrete Restoration Systems INC | Thomas Lawrence Trimm | — | (714) 996 3177 | Restoration | Placentia · Orange County | — | — |
| Concrete Resurfacing Services | Javier Albert Gonzalez | — | (949) 466 8970 | Other | Irvine · Orange County | — | — |
| Concrete Sealing Concepts | Joshua Michael Russell | — | (714) 381 8982 | GC, remodel, ADU | Orange · Orange County | — | — |
| Concrete Services And Equipment | Clifton Albert Auerswald | — | (714) 812 8173 | Other | Capistrano Beach · Orange County | — | — |
| Concrete Solutions | Jeff Robert Vasconcellos | — | (714) 749 8811 | Other | Orange · Orange County | — | — |
| Concrete Wave Design | Brock Logan Ii Greenberg | — | (866) 533 6455 | Other | Anaheim · Orange County | — | — |
| Concrete Workshop Co | Kenneth William Long | — | (714) 908 5505 | Other | Tustin · Orange County | — | — |
| Concrete Worx INC | Keith Raymond Denato | — | (714) 936 9155 | GC, remodel, ADU | Fullerton · Orange County | — | — |
| Concrete-surfaces INC | Andres Leal | — | (619) 643 8273 | Other | Orange · Orange County | — | — |
| Conejo Construction | Jimmy Avila Isais | — | (714) 585 1447 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Conley Design | Conley Design | — | (949) 244 6181 | GC, remodel, ADU | Laguna Beach · Orange County | — | — |
| Conncam Contractors | Jon Murvin Cameron | — | (949) 423 8050 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| Connected Heating & Air Corporation | Duane Michael Kressin | — | (714) 272 0903 | HVAC | Tustin · Orange County | — | — |
| Connex LLC | Michael Gregory Cruz | — | (909) 708 7509 | Other | Santa Ana · Orange County | — | — |