| Cornell Landscaping & Maintenance | Cornell Landscaping & Maintenance | — | (925) 820 6024 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Cornell Roofing Company INC | Clint Kennith Rich White | — | (925) 682 3473 | Other roofers | Concord · Contra Costa County | — | — |
| Cornerstone Builders | Cornerstone Builders | — | (925) 283 2256 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Cornerstone Construction | Onaje Timothy Boone | gwebb@cornerstone-construction.com | (832) 259-2520 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Cornerstone Environmental Contractors INC | Ronald Allen Harvey | — | (925) 299 9225 | Electricians | Concord · Contra Costa County | — | — |
| Cornerstone General Construction | Francisco Xavier Hernandez | — | (925) 759 0904 | Electricians | Pittsburg · Contra Costa County | — | — |
| Cornerstone Home Improvements | John Anthony Douglas | — | (925) 680 1762 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Cornish Contracting | Robert Clayton Cornish | — | (925) 595 2420 | GC, remodel, ADU | Bethel Island · Contra Costa County | — | — |
| Corona Builders Masonry INC | Corona Osorio Jaime | — | (925) 240 1424 | Other | Brentwood · Contra Costa County | — | — |
| Corona Painting | Corona Painting | — | (510) 375 6812 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Corral Communications | Corral Communications | — | (925) 216 3600 | Other | Pittsburg · Contra Costa County | — | — |
| Corrosion Concrete Related Services | Dean Trevor Rookes | — | (403) 874 6215 | Other | San Ramon · Contra Costa County | — | — |
| Corsa Plumbing And Rooter | Raymundo Alvarado Ramirez | — | (925) 826 9248 | Other | Pleasant Hill · Contra Costa County | — | — |
| Cort-yard Landscape | Cort-yard Landscape | — | (925) 437 4633 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Cosmi Construction | Dominic Vincent Cosmi | — | (925) 817 8953 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Cosmic Renovation | Zadok Sagi | — | (818) 497 4929 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Coss General Construction | Coss Chavez Jonatan | — | (415) 637 3034 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Costa Demolition | Costa Demolition | — | (415) 390 2590 | Other | El Cerrito · Contra Costa County | — | — |
| Coster Construction | Fredrick Alvin Jr Coster | — | (925) 367 5298 | GC, remodel, ADU | Bethel Island · Contra Costa County | — | — |
| Cottage Landscaping | Anthony Jon Franchetto | — | (925) 625 8404 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| Councell Heating And Air | Councell Heating And Air | — | (925) 206 8095 | HVAC | Antioch · Contra Costa County | — | — |
| Countertop Connection | Countertop Connection | — | (510) 734 5985 | Other | Pacheco · Contra Costa County | — | — |
| Countertops By Steve | Countertops By Steve | steveracer15c@gmail.com | (925) 625 5959 | Other | Knightsen · Contra Costa County | — | — |
| County Electric | Bill Virvitch | — | (925) 639 2090 | Electricians | Walnut Creek · Contra Costa County | — | — |
| Covalent Controls INC | Brooks Owen Wristen | info@covalentcontrols.com | (925) 477-2955 | Electricians | Concord · Contra Costa County | — | — |
| Covalt Communications | Covalt Communications | — | (925) 993 8053 | Other | Clayton · Contra Costa County | — | — |
| Covenant Technical Solutions INC | Sean Patrick Summers | info@covenanttechnicalsolutions.com | (925) 967 5232 | Other | Danville · Contra Costa County | — | — |
| Cowan & Thompson Construction INC | Barry James Thompson | — | (925) 372 9412 | Other | Martinez · Contra Costa County | — | — |
| Cozy Conditions HVAC | Cozy Conditions HVAC | — | (925) 477 0340 | HVAC | Antioch · Contra Costa County | — | — |
| Cpt Builders | William Harold Jr Mc Ferren | — | (925) 588 9137 | GC, remodel, ADU | Bay Point · Contra Costa County | — | — |
| Cr Gutters | Christopher Ryan Seeger | impallari@gmail.com | (408) 309 2767 | Other | Orinda · Contra Costa County | — | — |
| Cr Landscaping Services Corp | Christian Raul Reyna Vallecillo | — | (925) 470 0673 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Cr Renovations Ca INC | Robert Raymond Techaira | — | (925) 999 6292 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Cr Windows & Doors | Cr Windows & Doors | crwindowsjesus@gmail.com | (510) 274-5389 | Windows, patio, painters | Hayward · Contra Costa County | — | — |
| Craft Master Construction | Marty Elvin Alfonso | — | (510) 469 8869 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Crafted Earth Design & Build | Afrin Mohammad Khaiser | team@craftedearthdesignbuild.com | (925) 205 8724 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Crafts Man Construction | Mahadeo Baldeo | — | (925) 436 2826 | GC, remodel, ADU | Bay Point · Contra Costa County | — | — |
| Craftsman Decks | Craftsman Decks | agustinamingote@gmail.com | (707) 548 9541 | Other | San Pablo · Contra Costa County | — | — |
| Craftsman Painting And Restoration | Craftsman Painting And Restoration | — | (925) 288 9518 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Craftwork Electric | Kevin Paul Johnson | — | (510) 551 5061 | Electricians | Richmond · Contra Costa County | — | — |