| A & G Energy Source INC | Arturo Gonzalez | — | (925) 305 7434 | Electricians | Antioch · Contra Costa County | — | — |
| A & G General Maintenance INC | Piceno Gricelda Gomez | — | (925) 565 5502 | Other | Antioch · Contra Costa County | — | — |
| A & G Masonry | Francisco Javier Arriaga | — | (510) 932 4652 | Other | Richmond · Contra Costa County | — | — |
| A & J Electric | Johnson Nguyen Tran | — | (925) 219 6886 | Electricians | Pittsburg · Contra Costa County | — | — |
| A & J Fencing | Justin Lyle Lena | — | (925) 939 2105 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| A & M Fire Protection | A & M Fire Protection | — | (510) 314 5613 | Other | Martinez · Contra Costa County | — | — |
| A & N Construction | Higinio Fidel Olivera | — | (209) 914 4019 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| A & N Gardening And Landscaping | Kitic Ljubo | — | (925) 984 9107 | Windows, patio, painters | Danville · Contra Costa County | — | — |
| A & R HVAC | A & R HVAC | — | (408) 999 0305 | HVAC | San Ramon · Contra Costa County | — | — |
| A & R Plumbing And Drain INC | Armin Jiovany Rios | — | (510) 609 2804 | Other | Richmond · Contra Costa County | — | — |
| A & R Tree Services INC | Giovanny Alexander Donado | — | (925) 510 4100 | Tree | Concord · Contra Costa County | — | — |
| A + Home Repair And Remodeling | Folke David | — | (925) 548 5535 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| A - 1 Planet Products INC | Dante Braz Queiroz | — | (510) 237 0008 | Other | Richmond · Contra Costa County | — | — |
| A - K Aeration & Landscaping | Ken Lee Kincaid | — | (925) 984 6883 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| A 1 World Class Painting | A 1 World Class Painting | — | (925) 497 6850 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| A A C Construction | Christian Jean Rousset | — | (925) 890 4482 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| A A Custom Construction Services A California Joint Venture | & D Plumbing A | — | (925) 922 4770 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| A B Builders INC | Hector Gallegos | — | (925) 759 3095 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| A B C Building & Restoration INC | James David Sutton | — | (925) 766 8383 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| A B O Landscaping | A B O Landscaping | — | (415) 488 7166 | Windows, patio, painters | Pinole · Contra Costa County | — | — |
| A Better Cabinet & Design | A Better Cabinet & Design | — | (510) 260 0590 | Other | El Cerrito · Contra Costa County | — | — |
| A C Electric | Noel Tria Santos | — | (510) 812 9029 | Electricians | Hercules · Contra Costa County | — | — |
| A C Heating & Cooling Service INC | Raul Fernando Valderrama | — | (925) 521 1807 | HVAC | Concord · Contra Costa County | — | — |
| A C Systems INC DBA Air Conditioning Systems | Joseph Anthony Allen | — | (925) 676 2103 | HVAC | Concord · Contra Costa County | — | — |
| A Cut Above Builders INC | David Preston Burchard | — | (925) 817 8231 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| A D Family Plumbing Services | Vasquez Alejandro Diaz | — | (510) 512 5029 | Other | Pittsburg · Contra Costa County | — | — |
| A D Hauling | A D Hauling | — | (510) 914 3740 | Other | Richmond · Contra Costa County | — | — |
| A D L Professional Insulation | Adolfo Daniel Luperdi | — | (408) 771 6324 | Other | Antioch · Contra Costa County | — | — |
| A E Flooring | A E Flooring | — | (661) 964 8585 | Other | Canyon · Contra Costa County | — | — |
| A Finished Home INC | Brian Patrick Kozera | brian@afinishedhome.com | (925) 915 0896 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| A G Construction | Jose Antonio Godinez | — | (510) 750 8234 | Other | Richmond · Contra Costa County | — | — |
| A G Drywall | A G Drywall | — | (813) 388-7563 | Other | Pacheco · Contra Costa County | — | — |
| A G Gardening Services | Gutierrez Arturo | — | (925) 383 7574 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| A G Heating & Air Conditioning | Gil Argueta Garcia | — | (925) 584 0800 | HVAC | Discovery Bay · Contra Costa County | — | — |
| A G Pavers | Anselmo Antonio Goulart | — | (925) 327 0804 | Other | San Ramon · Contra Costa County | — | — |
| A J A General Construction | Angelo John Arminio | — | (510) 604 8894 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| A J C Design And Construction INC | Juan Bernardo Ortiz Lemus | — | (510) 478 6644 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| A L B INC | Robert Jr Gonzalez | — | (925) 427 1199 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| A L Hardwood Floors | A L Hardwood Floors | — | (925) 943 1107 | Other | Walnut Creek · Contra Costa County | — | — |
| A L P Construction | Adrian Lopez Perez | — | (415) 336 9145 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |