| A L P Painting And Decorating INC | Adrian Lopez Perez | — | (415) 336 9145 | Windows, patio, painters | Pleasant Hill · Contra Costa County | — | — |
| A L Venegas Construction | Anthony Louis Venegas | — | (925) 339 6615 | GC, remodel, ADU | Pacheco · Contra Costa County | — | — |
| A M A C Construction & Restoration | Tyler Lynn Douglass | — | (925) 356 2619 | Electricians | Walnut Creek · Contra Costa County | — | — |
| A M G Electric | Anthony Michael Granelli | — | (925) 963 5256 | Electricians | Martinez · Contra Costa County | — | — |
| A M P Painting | A M P Painting | — | (415) 240 5196 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| A Manecer Landscape | A Manecer Landscape | — | (925) 567 6367 | Windows, patio, painters | Orinda · Contra Costa County | — | — |
| A Meadows Construction INC | Aaron Anthony Meadows | — | (925) 625 4951 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| A Meono Painting | A Meono Painting | — | (415) 846 0167 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| A O Jones Paving INC | John Larry Jones | anapbm@gmail.com | (925) 439 7027 | Other | Pittsburg · Contra Costa County | — | — |
| A O L Painting | A O L Painting | — | (925) 597 2417 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| A P C O Construction | Kimberly Yvett Avila | — | (925) 680 7397 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| A Plus Plumbing | A Plus Plumbing | aplusplumbingser@gmail.com | (925) 383 8499 | Other | Discovery Bay · Contra Costa County | — | — |
| A R G Mobile Welding | A R G Mobile Welding | argwelding1@gmail.com | (510) 253 9133 | Other | Richmond · Contra Costa County | — | — |
| A R Glass | A R Glass | — | (415) 933 7632 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| A Ramos Construction INC | Ramos-avila Agapito | — | (925) 766 7960 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| A S A P Heating & Cooling | Curtis Mitchell Orloff | — | (925) 876 1900 | HVAC | Concord · Contra Costa County | — | — |
| A S D Woodworks INC | Steve Perry Glover | — | (925) 216 3622 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| A S I Alarms | Robert Louis Mundo | info@asialarms.com | (800) 408 4338 | Electricians | Concord · Contra Costa County | — | — |
| A S I Systems INC | Jason Aaron Jones | — | (888) 944 7274 | Electricians | Martinez · Contra Costa County | — | — |
| A S K Construction INC | Adam Spencer Kittredge | — | (925) 848 4993 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| A S Landscaping Maintenance | A S Landscaping Maintenance | — | (925) 370 8356 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| A S Remodeling Construction | Sanchez Chavez Alfredo | — | (510) 860 9470 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| A S T Installations | A S T Installations | — | (415) 424 8094 | Other | Oakley · Contra Costa County | — | — |
| A T Construction | Allen Ka Wai Tam | — | (510) 367 7795 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| A T S Communications INC | Thomas Paul Klosterman | — | (925) 602 1500 | Other | Concord · Contra Costa County | — | — |
| A To Z Plumbing & Heating Services INC | Mansour Matthew Azizi | — | (510) 359 8870 | HVAC | Brentwood · Contra Costa County | — | — |
| A V R Heating & Cooling Service | Raul Steve Valderrama | — | (925) 595 2009 | HVAC | Concord · Contra Costa County | — | — |
| A V Structural INC DBA A V Company | Katheryn Vykhanhtrong Nguyen | — | (415) 386 8086 | Other | Concord · Contra Costa County | — | — |
| A W S Partners INC | Grant Austin Adams | — | (925) 413 7268 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| A#1 Developers INC | Joseph John Rezek | — | (510) 378 8884 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| A&j Outdoor Solutions | Dean William Henninger | — | (510) 221 7246 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| A&r Builder Pro | Victor Alfonso Rivera | — | (925) 518 4079 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| A+ Painting INC | Francisco Luna | — | (925) 375 0559 | Windows, patio, painters | Pinole · Contra Costa County | — | — |
| A+ Plus Roofing | Mark Edward Kuizin | — | (916) 206 7320 | Other roofers | Pleasant Hill · Contra Costa County | — | — |
| A-1 Fire Protection Services INC | Doyle Delon Muhammad | — | (925) 305 5884 | Other | Oakley · Contra Costa County | — | — |
| A-1 Pro Construction LLC | Nicklesh Avtar Johal | — | (925) 236 0776 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| A-2-z Services | Michael Nathaniel Austin | — | (925) 323 2872 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| A-list Landscape LLC | Catlina Guadalupe Holani | — | (925) 430 8326 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| A-plus Painting Company INC | Juan Enrique Salazar | — | (925) 325 7949 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| A-s Pipelines INC | John Paul Arcidiacono | — | (925) 671 7711 | Other | Concord · Contra Costa County | — | — |