| Advanced Water Well Drilling & Pump Services | William Chester Houck | — | (925) 785 2015 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Advantage Pools Bay Area | Advantage Pools Bay Area | — | (925) 628 0594 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Advantage Pools Bay Area INC | David Brian Cardiff | — | (925) 628 0594 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Ae2j Rueda Construction | Gomez Adolfo Rueda | — | (707) 419 2384 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Aei Consultants | Craig Harold Hertz | — | (925) 746 6071 | Other | Walnut Creek · Contra Costa County | — | — |
| Aep Construction | Anthony Eric Parrish | — | (510) 586 1566 | GC, remodel, ADU | Rodeo · Contra Costa County | — | — |
| Af Roofing & Siding INC | Miguel Angel Franco Salinas | afroofingandsidinginc.2021@gmail.com | (510) 323 6220 | Other roofers | San Pablo · Contra Costa County | — | — |
| Af Woodworker INC | Christopher Mitchell Nash | a.alamir@afwoodworker.com | (510) 717 7378 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Affinity Construction | Andy George Vasiloudis | info@affinity-construction.com | (415) 740 1482 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Affinity Waterscapes | Affinity Waterscapes | info@affinitywaterscapes.com | (925) 465 4517 | Pool | Lafayette · Contra Costa County | — | — |
| Affordable Electric | Scott Alan Portier | — | (925) 285 3119 | Electricians | Bay Point · Contra Costa County | — | — |
| Affordable Roofing Systems | Affordable Roofing Systems | — | (925) 381-9162 | Other roofers | Martinez · Contra Costa County | — | — |
| Ag General Construction | Jose Alfredo Garcia | — | (510) 927 5640 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Ag Landscaping & Maintenance LLC | Alvaro Gonzalez | — | (925) 698 3194 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Ag Welding | Ag Welding | info@agwelding.com | (510) 551 8783 | Other | Pinole · Contra Costa County | — | — |
| Aga Painting | Aga Painting | — | (510) 599 7526 | Windows, patio, painters | San Pablo · Contra Costa County | — | — |
| Agama Painting | Agama Painting | — | (650) 892 1584 | Windows, patio, painters | Pleasant Hill · Contra Costa County | — | — |
| Agc Concrete | Agc Concrete | — | (510) 613 5511 | Other | El Cerrito · Contra Costa County | — | — |
| Agr General Engineering Contractor | Agr General Engineering Contractor | — | (510) 730 6612 | Other | Richmond · Contra Costa County | — | — |
| Agt Builders INC | Tevita Sioeli Lauaki | — | (808) 780 0177 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Aguayo Electrical Services | Luis Aguayo-Lopez | — | (925) 787 0712 | Electricians | Concord · Contra Costa County | — | — |
| Aguilar Construction | Aguilar Sergio | — | (925) 325 7974 | GC, remodel, ADU | Bay Point · Contra Costa County | — | — |
| Aguilar Construction | Jose Guerra Aguilar | — | (510) 376 5287 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Aguilar Floor Covering | Aguilar Floor Covering | — | (925) 917 4040 | Other | Rodeo · Contra Costa County | — | — |
| Aguilar Pool Service | Rickie Anthony Aguilar | — | (925) 627 0568 | Pool | Oakley · Contra Costa County | — | — |
| Aguilera Properties | Aguilera Properties | — | (510) 520 9615 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Aguinava Electric INC | Juan Carlos Navarrete Zavala | — | (510) 932 7151 | Electricians | San Pablo · Contra Costa County | — | — |
| Agurto Corporation | Luis Aurelio Agurto | — | (925) 757 2945 | Other | Antioch · Contra Costa County | — | — |
| Ahmad Jamel Zahran | Ahmad Jamel Zahran | — | (310) 500 9867 | Electricians | Richmond · Contra Costa County | — | — |
| Ahs Landscaping INC | Sergio Guadalupe Macedo Abando | — | (925) 899 3703 | Windows, patio, painters | Clayton · Contra Costa County | — | — |
| Ahumada General Construction | Hector Alejandro Ahumada | — | (510) 367 7267 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Aiello Painting | Gary Fredrick Aiello | — | (925) 864 9284 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Air - Con Mechanical Services INC | Joseph Carl Condon | — | (925) 279 3330 | HVAC | Walnut Creek · Contra Costa County | — | — |
| Air Brothers Mechanical INC | Christopher Michael Poshinske | — | (925) 477 8906 | HVAC | Discovery Bay · Contra Costa County | — | — |
| Air Control | James Alan Crowson | interested@domainmarket.com | (925) 938 4822 | HVAC | Lafayette · Contra Costa County | — | — |
| Air Design Heating & Cooling | Air Design Heating & Cooling | — | (925) 837 4328 | HVAC | Danville · Contra Costa County | — | — |
| Air Doctors Heating & Cooling | Air Doctors Heating & Cooling | — | (615) 242-1230 | HVAC | Walnut Creek · Contra Costa County | — | — |
| Air Experts | Byron Eric| Smith Eric Smith | — | (925) 625 5458 | HVAC | Brentwood · Contra Costa County | — | — |
| Air Masters Heating And Air Conditioning INC | Brandon James Gault | — | (925) 855 1560 | HVAC | Discovery Bay · Contra Costa County | — | — |
| Air Mechanics INC | Luis Alonso Colmenares | — | (925) 513 0804 | HVAC | Brentwood · Contra Costa County | — | — |