| Costa Mesa Painting INC | Nava Fabiola Espinoza | — | (949) 204 9094 | Windows, patio, painters | Costa Mesa · Orange County | — | — |
| Costa Mesa Roofers | Costa Mesa Roofers | — | (949) 390-6295 | Other roofers | Costa Mesa · Orange County | — | — |
| Costa Outdoor Living | Costa Outdoor Living | — | (949) 320 3433 | GC, remodel, ADU | San Juan Capistrano · Orange County | — | — |
| Costa Verde Landscape INC | Terrence John Jr Mc Cann | — | (714) 668 9900 | Windows, patio, painters | Lake Forest · Orange County | — | — |
| Costello Construction | Patrick Joseph Costello | — | (949) 768 4292 | GC, remodel, ADU | Mission Viejo · Orange County | — | — |
| Coster Construction | Steven Peter Coster | — | (562) 522 2020 | GC, remodel, ADU | Seal Beach · Orange County | — | — |
| Costera Waste & Environmental | Michael John Jr Bruno | — | (415) 646 3546 | Other | Rancho Santa Margarita · Orange County | — | — |
| Costescu Construction | Costescu Ioan | — | (714) 319 6803 | GC, remodel, ADU | Garden Grove · Orange County | — | — |
| Costiero Contracting INC | John Christopher Birkett | — | (562) 577 9581 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Cote Tile | Cote Tile | — | (714) 329 7495 | Other | Fountain Valley · Orange County | — | — |
| Coto Glass INC | Estefany Christina Panduro | — | (949) 872 5544 | Windows, patio, painters | Rancho Santa Margarita · Orange County | — | — |
| Cottage Construction | Dennis Ryan Grob | — | (949) 943 7671 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| County Heating And Air Conditioning Incorporated | Adam James Gadomski | — | (714) 639 9981 | HVAC | Orange · Orange County | — | — |
| County Wide Plumbing Heating Rooter & Air | Rick Joseph Edwards | — | (714) 540 7095 | HVAC | Orange · Orange County | — | — |
| Courtney Construction | Joseph Martin Gonzales | — | (949) 689 5910 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| Courtney INC | George Garland Iii Courtney | — | (949) 222 2050 | Other roofers | Irvine · Orange County | — | — |
| Cousens Construction INC | Paul Albert Cousens | — | (818) 522 8080 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Cousyn Grading & Demo INC | David Jason Cousyn | — | (714) 557 1566 | Other | Fountain Valley · Orange County | — | — |
| Covalt Floor Leveling | Covalt Floor Leveling | — | (949) 496 3528 | Other | San Juan Capistrano · Orange County | — | — |
| Cove Concrete INC | Joshua Logan Hunter | — | (949) 482 6982 | Other | Ladera Ranch · Orange County | — | — |
| Cove Custom Homes LLC | Darin Scott Colton | — | (949) 322 8662 | GC, remodel, ADU | Dana Point · Orange County | — | — |
| Covenant Air Systems INC | Roger Alan Smith | — | (714) 990 1799 | HVAC | Brea · Orange County | — | — |
| Covenant Construction | Peyam Mirzaei | — | (760) 718 9652 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| Covenant Design Build & Construction Management INC | Weiping Tu | — | (657) 400 6712 | Electricians | Irvine · Orange County | — | — |
| Coventry Construction Services INC | Darryl Lee Mitchell | — | (714) 337 8603 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| Cover Right Roofing INC | Mark Richard Billings | inquiries.coverright@gmail.com | (714) 832 0113 | Other roofers | Santa Ana · Orange County | — | — |
| Covering Orange County | Covering Orange County | — | (949) 419 5647 | Windows, patio, painters | Tustin · Orange County | — | — |
| Covi Concrete Construction INC | Paul Covi Bissin | — | (714) 842 3185 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Covi Hardscape And Landscape | Cortes Vivanco Fernando | — | (714) 423 5579 | Windows, patio, painters | Garden Grove · Orange County | — | — |
| Covington Custom Flooring INC | Chase Christian Covington | — | (714) 814 7100 | Other | Orange · Orange County | — | — |
| Covington Development INC | Gary Jay Covington | — | (714) 309 0425 | GC, remodel, ADU | Los Alamitos · Orange County | — | — |
| Covoc Corporation | Molly Suzanne Condon | — | (714) 879 0341 | Other | Fullerton · Orange County | — | — |
| Cowan Construction | Kenneth Daniel Cowan | — | (707) 218 7030 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Cowan Electric | James Gordon Cowan | cowanelectric@yahoo.com | (949) 683 9030 | Electricians | San Clemente · Orange County | — | — |
| Cowdell Construction Concepts | Robert David Cowdell | — | (949) 751 7036 | GC, remodel, ADU | Tustin · Orange County | — | — |
| Cowles Electric | Raymond Stuart Cowles | — | (714) 519 8445 | Electricians | Anaheim · Orange County | — | — |
| Cox Contracting Services INC | Stephanie Georgann Cox | — | (949) 355 4499 | GC, remodel, ADU | Laguna Beach · Orange County | — | — |
| Cox Homes | Cox Homes | — | (714) 827 2334 | GC, remodel, ADU | Cypress · Orange County | — | — |
| Cox Testing & Compliance | Cox Testing & Compliance | — | (714) 334 3693 | Other | Fullerton · Orange County | — | — |
| Cox-novak Construction INC | Darryl Charles Shedarowich | — | (949) 505 3261 | GC, remodel, ADU | Trabuco Canyon · Orange County | — | — |