| Custom Pro Construction INC DBA Custom Pro Concrete | Miguel Angel Gonzalez Vazquez | — | (714) 317 6883 | Pool | Santa Ana · Orange County | — | — |
| Custom Quality Electric INC | Ryan Lance Scott | — | (714) 541 0404 | Electricians | Tustin · Orange County | — | — |
| Custom Security Services | Joe Iii Valenzuela | — | (562) 665 9791 | Electricians | La Habra · Orange County | — | — |
| Custom Wall And Ceiling Systems | Custom Wall And Ceiling Systems | — | (714) 249 0290 | Other | Buena Park · Orange County | — | — |
| Custom Wallcovering Company | Joseph Anthony Foeldi | — | (714) 822 6220 | Windows, patio, painters | Huntington Beach · Orange County | — | — |
| Custom Weatherstrip INC | Michael Patrick Siebuhr | — | (714) 662 1574 | Other | Costa Mesa · Orange County | — | — |
| Custom Wood Interiors | Vernon Joseph Ellender | — | (949) 366 0181 | Other | San Clemente · Orange County | — | — |
| Custom-built Construction | Do Hamilton | — | (626) 242 7503 | GC, remodel, ADU | Westminster · Orange County | — | — |
| Customer Care Plumbing & Drains | Geobani Murillo | — | (714) 696 4754 | Other | Anaheim · Orange County | — | — |
| Customz Design & Builder | Customz Design & Builder | — | (949) 291 3430 | Electricians | Dana Point · Orange County | — | — |
| Customz General Contracting | Anthony Crawford Lewis | — | (760) 802 5565 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Cut Above Construction & Design INC | Jeremy Scott Wray | — | (714) 458 9202 | GC, remodel, ADU | Fountain Valley · Orange County | — | — |
| Cut Above Landscape Maintenance INC A | Richard Jay Kington | — | (949) 643 2178 | Windows, patio, painters | Laguna Niguel · Orange County | — | — |
| Cuthill Plumbing | Cuthill Plumbing | — | (714) 317 0705 | Other | Costa Mesa · Orange County | — | — |
| Cutler Construction Services INC | Joshua Adam Cutler | — | (855) 805 2274 | GC, remodel, ADU | Orange · Orange County | — | — |
| Cutting Edge Building Company | Aldo Ariel Cruz Davalos | sales@cuttingedgebuilding.com.au | (714) 294 0010 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Cutting Edge Millworks | Nickolas Benjamin Peterson | — | (949) 910 0590 | GC, remodel, ADU | Aliso Viejo · Orange County | — | — |
| Cutting Edge Services INC | Mark Vincent Graeff | — | (310) 344 8817 | HVAC | Orange · Orange County | — | — |
| Cutwater Heating & Air | Cutwater Heating & Air | — | (949) 525 8654 | HVAC | Laguna Niguel · Orange County | — | — |
| Cvcr INC | Forrest Lee Gregge | — | (805) 768 5199 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Cw Building | Cw Building | — | (949) 307 6278 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| Cwd Electric INC | Charles William Iii Donohue | — | (714) 412 1199 | Electricians | Costa Mesa · Orange County | — | — |
| Cy Blady | Cy Blady | — | (504) 338 7564 | GC, remodel, ADU | Yorba Linda · Orange County | — | — |
| Cy Empire Construction INC | Yong Hoe Ho | chris@cyempireconstruction.com | (949) 742 0496 | GC, remodel, ADU | Orange · Orange County | — | — |
| Cybertech Development INC | Gerardo Saul Alcantara Garcia | info@cybertech-development.com | (714) 363-3553 | GC, remodel, ADU | Orange · Orange County | — | — |
| Cybertech Electric | Gerardo Saul Alcantara Garcia | — | (714) 488 3576 | Electricians | Orange · Orange County | — | — |
| Cybex Security Solutions L L C | Jason Michael Martin | — | (800) 749 2939 | Electricians | Irvine · Orange County | — | — |
| Cycle Heating And Air LLC | Derek John Clayson | — | (949) 212 8582 | HVAC | Laguna Hills · Orange County | — | — |
| Cymru Trading INC DBA Hart's Rugs & Carpets | Phillip Bede Willia Hart | — | (714) 434 8440 | Other | Costa Mesa · Orange County | — | — |
| Cypress Bath LLC | Michael Paul Guzman | — | (310) 560 8519 | GC, remodel, ADU | Buena Park · Orange County | — | — |
| Cyrus Company | Cyrus Mohammad Hosseini | — | (562) 572 4040 | Other | La Habra · Orange County | — | — |
| Cyrus Contractors INC | Siamak Namiranian | — | (858) 688 4757 | GC, remodel, ADU | Laguna Niguel · Orange County | — | — |
| Cys Company | Calvin Youngsok Song | — | (714) 395 8504 | GC, remodel, ADU | Brea · Orange County | — | — |
| Cz Electric | Csernus Zoltan | cz_electric@msn.com | (714) 264 3206 | Electricians | Anaheim · Orange County | — | — |
| Czar Electric | Colin Agustus Caesar | — | (562) 248 2442 | Electricians | Los Alamitos · Orange County | — | — |
| D & C Slurry & Striping INC | Daniel Thomas Maas | — | (714) 444 2060 | Other | La Habra · Orange County | — | — |
| D & D Consulting And Development | Doru V Botic | — | (949) 294 2396 | GC, remodel, ADU | Rancho Santa Margarita · Orange County | — | — |
| D & D Development Company | Dell George Dohrman | — | (714) 671 1400 | GC, remodel, ADU | Brea · Orange County | — | — |
| D & D Plumbing Services INC | Vergara Quiroz Graciano | — | (949) 813 0256 | Other | Laguna Hills · Orange County | — | — |
| D & D Sign Service | Tim Raynor Holmes | — | (562) 690 5622 | Other | Brea · Orange County | — | — |