| California Trenchless INC | Michael Byron Jardin | mjardin@californiatrenchless.com | (510) 782 5335 | Other | Hayward · Alameda County | — | — |
| California's Gunite & Pool Plastering INC | Manuel Rodriguez | — | (925) 960 9500 | Pool | Livermore · Alameda County | — | — |
| Calime Engineering & Construction | Michael Njoroge Wandiga | — | (866) 611 7852 | GC, remodel, ADU | Dublin · Alameda County | — | — |
| Calisign | Michael James Twomey | — | (925) 420 7075 | Other | Livermore · Alameda County | — | — |
| Calmo's Plumbing & Rooter INC | Hassan Mirzai | — | (510) 365 7787 | Other | Oakland · Alameda County | — | — |
| Calnatural Landscape | Calnatural Landscape | — | (510) 689 4525 | Windows, patio, painters | Hayward · Alameda County | — | — |
| Calsan C&d Waste Removal | Perez Fidel Calva | — | (510) 328 9384 | Other | Alameda · Alameda County | — | — |
| Calstate Construction INC | Andrew Thomas Borrego | amkryukov@gmail.com | (510) 657 1800 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| Calsun Energy INC | Ren-Chau James Hu | — | (415) 260 0611 | Electricians | San Leandro · Alameda County | — | — |
| Calsystem Restoration Services INC | Gonzalez Gonzalo | — | (510) 430 0226 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Camacho's Concrete Flatwork INC | Jose Quintin Camacho Perez | — | (650) 274 1153 | Other | Hayward · Alameda County | — | — |
| Camco Builders | Camco Builders | — | (925) 872 3222 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Camello INC | Shaun Michael Morrison | — | (510) 567 3980 | GC, remodel, ADU | Castro Valley · Alameda County | — | — |
| Cameron Graham | Cameron Graham | — | (925) 337 5181 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Campos Construction | Francisco Javier Campos Guzman | — | (510) 565 5728 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| Campos Electric | Fernando Gerardo Campos | — | (510) 378 7344 | Electricians | Fremont · Alameda County | — | — |
| Can Am Construction Cleanup | Ali Mohammed | — | (510) 755 1133 | Other | Hayward · Alameda County | — | — |
| Can Hoa Ly | Can Hoa Ly | — | (510) 351 3288 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| Can-am Plumbing INC | Michael Frank Capilla | canam@canamplumbing.com | (925) 846 1833 | Other | Pleasanton · Alameda County | — | — |
| Canivet Construction INC | Guillaume Rene Canivet | — | (510) 528 3700 | GC, remodel, ADU | Albany · Alameda County | — | — |
| Cano Landscaping | Cano Landscaping | — | (510) 701 2036 | Windows, patio, painters | Oakland · Alameda County | — | — |
| Cano-eixo Construction INC | Aleixo Sergio Vicente Chumbeiro | — | (925) 200 6775 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| Canova Marble INC | Robert Yako Toma | — | (510) 568 3203 | Other | Oakland · Alameda County | — | — |
| Canyon Builder INC | Yit Se Liu | — | (510) 719 8961 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Canyon Design Build | Christopher Stephen Avant | — | (510) 482 0300 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Capelli Plumbing INC | James Paul Capelli | capelliplumbing@gmail.com | (510) 969 4358 | Other | San Leandro · Alameda County | — | — |
| Capeta Radiant Heat Systems | Capeta Radiant Heat Systems | — | (510) 384 6710 | HVAC | Oakland · Alameda County | — | — |
| Capital Automatic Gates | Capital Automatic Gates | — | (510) 292 7819 | Other | Hayward · Alameda County | — | — |
| Capital Caulking & Waterproofing Corp | Shaun Allen Steinbach | — | (510) 754 5605 | Windows, patio, painters | Dublin · Alameda County | — | — |
| Capital Electric & Sign Co | Donald David Deluze | — | (408) 892 6744 | Other | Fremont · Alameda County | — | — |
| Capitol Glass Co | Matthew Anthony Jurado | — | (510) 786 4200 | Windows, patio, painters | Hayward · Alameda County | — | — |
| Cappa & Co Builders | Caitlin Cappa Nunez | — | (925) 324 4442 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| Capurro Family Plumbing | Capurro Family Plumbing | — | (510) 220 6697 | Other | Oakland · Alameda County | — | — |
| Carcon International Ltd | Kenneth Philip Carvalho | — | (510) 381 3527 | GC, remodel, ADU | Alameda · Alameda County | — | — |
| Cardenas Custom Builders INC | Cardenas Grimaldo Alfredo | info@cardenascustombuilders.com | (650) 892 4304 | GC, remodel, ADU | Hayward · Alameda County | — | — |
| Cardinal Builder INC | Anthony Hughes Neto | aneto@cardinalbuilder.com | (925) 913 0517 | GC, remodel, ADU | Pleasanton · Alameda County | — | — |
| Cardona Plumbing | Cardona Plumbing | cardonaplumbing@yahoo.com | (925) 548 8102 | Other | Dublin · Alameda County | — | — |
| Care Heating & Air Conditioning INC | Jose Alonso Gutierrez | info@careheatingaircondtioninginc.com | (510) 798 7944 | HVAC | Oakland · Alameda County | — | — |
| Carefree Toland Pools INC | Karan Laurine Toland | — | (925) 462 1441 | Pool | Livermore · Alameda County | — | — |
| Carfam Construction | Michael David Cardoze | — | (510) 706 5280 | GC, remodel, ADU | Hayward · Alameda County | — | — |