| Apollo Roofing Company | George Cesar Jr Arrospide | — | (925) 860 3538 | Other roofers | Walnut Creek · Contra Costa County | — | — |
| Apple Landscaping | Apple Landscaping | — | (925) 726 5868 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Aps Painting | Aps Painting | — | (925) 238 1916 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Aqua Dream Pools | Anne Polce | — | (925) 584 2112 | Pool | Danville · Contra Costa County | — | — |
| Aqua Duct Commercial Plumbing INC | Tzorbatzakis Michael | — | (510) 595 1458 | Other | Moraga · Contra Costa County | — | — |
| Aqua Pool Company Inc. | Aqua Pool Company Inc. | — | (925) 938-1441 | Pool | Concord · Contra Costa County | — | — |
| Aqua Pool Construction LLC | Craig Allen Marker | todd@aquapoolconstruction.com | (925) 890 1596 | Pool | Concord · Contra Costa County | — | — |
| Aqua Systems Plumbing | Aqua Systems Plumbing | — | (408) 881 4472 | Other | Concord · Contra Costa County | — | — |
| Aquamatic Fire Protection INC | Christopher Michael Fredenburg | — | (925) 753 0420 | Other | Pittsburg · Contra Costa County | — | — |
| Aquapro Pool & Chemical INC | Jason Everett Mc Killip | — | (925) 673 7000 | Pool | Clayton · Contra Costa County | — | — |
| Aquatic Harvesting | Rick Lee Hatton | — | (925) 786 0095 | Other | Danville · Contra Costa County | — | — |
| Aquatic Leak Detection | Katherine Mary Vieira | — | (925) 372 7145 | Pool | Danville · Contra Costa County | — | — |
| Aquatic Pool And Spa Maintanence Experts | Faraz Soltani | — | (925) 510 0988 | Pool | Pleasant Hill · Contra Costa County | — | — |
| Ar Constructive INC | Joorabchi Arash Erfani | — | (925) 255 6077 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Ar Home Improvements | Edgar Gerardo Alvarez Venegas | enquiries@arhomeimprovements.com | (510) 942 1790 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Arad Engineering & Construction | Ata Radfar | — | (415) 816 2048 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Arastek LLC | Majid Talebzadeh | — | (925) 785 2553 | HVAC | San Ramon · Contra Costa County | — | — |
| Arborland Tree Service INC | Nelzon Arturo Castellanos | arborlandtreeservice@yahoo.com | (925) 497-2271 | Tree | Concord · Contra Costa County | — | — |
| Arc Construction | Ahmad Reza Rassai | — | (925) 478 9397 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Arc Construction A Partnership | Cary Lee French | — | (925) 785 0060 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Arc Water Damage | Arc Water Damage | — | (877) 437-9225 | Restoration | Lafayette · Contra Costa County | — | — |
| Archi's Painting Co | Jesus Antonio Archi Aguilar | — | (925) 698 8865 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Archidesign | Peter Jay Wiitala | — | (925) 202 3520 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Arctic Refrigeration INC | Beverly Jean Mossotto | — | (925) 686 0923 | HVAC | Concord · Contra Costa County | — | — |
| Arellano Bay Construction | Jose Heraclio Arellano Cardenas | — | (510) 478 6095 | Electricians | San Pablo · Contra Costa County | — | — |
| Arete Audiovisual Design INC | Bruce Jeffery Green | — | (650) 222 4841 | Electricians | Brentwood · Contra Costa County | — | — |
| Arg Construction | Ismael Argueta Umanzor | — | (510) 660 7332 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Arg Construction Services | Austin Richard Gentry | — | (925) 963 2379 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Arg Renovation And Construction | Shahin Noorieh Mehdiabadi | — | (510) 501 1988 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Argenal Construction LLC | Javan Nehemiah Argenal | — | (925) 436 2210 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Arguello's General Construction | Jason Gene Arguello | — | (510) 837 8424 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Aria Construction Enterprise INC DBA Uv Electric Company | Bob Mirzai | — | (925) 415 6090 | Electricians | Lafayette · Contra Costa County | — | — |
| Aria Marble And Tile | Aria Marble And Tile | — | (925) 282 0680 | Other | Oakley · Contra Costa County | — | — |
| Aria Rafaat | Aria Rafaat | — | (510) 926 2622 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Arias Concrete Contractor | Arias Concrete Contractor | — | (925) 446 2492 | Other | Pittsburg · Contra Costa County | — | — |
| Ariel HVAC Solutions INC | Olakunle Owolabi Olusesi | arielhvacsolutions@gmail.com | (415) 882 6888 | HVAC | Clayton · Contra Costa County | — | — |
| Aries Builders INC | Timothy Eugene Shannon | — | (925) 250 3803 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Aries Millwork & Construction | Aries Arroyo Sosa | — | (925) 522 6934 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Arin Corey Construction INC | Arin Michael Corey | — | (510) 685 7207 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Arisalva Construction | Orlando Aristides Morales Argueta | — | (415) 319 4294 | GC, remodel, ADU | Concord · Contra Costa County | — | — |