| Air Men Heating And Air Conditioning | Samuel Sr Arguello | — | (925) 755 9261 | HVAC | Walnut Creek · Contra Costa County | — | — |
| Air Performance Heating & Cooling LLC | John Edward Freij | — | (925) 899 0174 | HVAC | San Ramon · Contra Costa County | — | — |
| Air Pro HVAC | Air Pro HVAC | — | (925) 768 3316 | HVAC | Concord · Contra Costa County | — | — |
| Air Science Technologies INC | Pedro Rubio | — | (510) 799 4638 | Other | Rodeo · Contra Costa County | — | — |
| Air Synergy INC | Mendez Alberto | info@airsynergy.com | (925) 510 2037 | HVAC | Pittsburg · Contra Costa County | — | — |
| Air Time Mechanical INC | Robert Edward Elmore | airtimemech@comcast.net | (925) 639 5233 | HVAC | Concord · Contra Costa County | — | — |
| Air Treatment | Air Treatment | — | (416) 235-0373 | HVAC | Walnut Creek · Contra Costa County | — | — |
| Airbee | Jose D Rodriguez | — | (925) 247 8241 | HVAC | Walnut Creek · Contra Costa County | — | — |
| Airflow Specialists | Airflow Specialists | — | (925) 597 0699 | HVAC | Brentwood · Contra Costa County | — | — |
| Airgonomics Heating & Cooling LLC | Charles Edward Gearheart | — | (925) 290 1000 | HVAC | Antioch · Contra Costa County | — | — |
| Airtight Construction INC | Dennis Jay Jones | — | (925) 687 1121 | Other roofers | Concord · Contra Costa County | — | — |
| Aix Construction INC | Larios Mario Salinas | — | (925) 324 0166 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Aj Construction | Jesus Gerardo Aguilera Orozco | info@aj-construction.com | (415) 756 9672 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Aj Floor Covering | Aj Floor Covering | — | (925) 565 8889 | Other | Pittsburg · Contra Costa County | — | — |
| Aj Genesis Painting | Jose Jony Romero De Paz | — | (925) 915 0487 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Aj's Landscaping | Christopher Robert Jehs | — | (925) 382 2139 | Windows, patio, painters | Knightsen · Contra Costa County | — | — |
| Ajp General Construction | Adolfo Jeronimo-Pina | — | (415) 519 0862 | Electricians | San Pablo · Contra Costa County | — | — |
| Ak Electric | Khosrowjah Ali | — | (510) 621 8405 | Electricians | El Sobrante · Contra Costa County | — | — |
| Aka Partner LLC | Jared Kapono Abrojena | — | (925) 584 7449 | Windows, patio, painters | Walnut Creek · Contra Costa County | — | — |
| Akd Homes INC | Allan Francisco Mejia | — | (650) 241 5381 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Akm Construction | Salome Raul Manzanarez | — | (510) 776 5035 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Al's Electric | Alvaro R Vasquez | — | (925) 584 7464 | Electricians | Pittsburg · Contra Costa County | — | — |
| Al's Plumbing Works | Al's Plumbing Works | — | (510) 557 6868 | Other | Antioch · Contra Costa County | — | — |
| Alamo Landscape LLC | Marco Antonio Cisneros | daniel.ochoa@alamo-landscape.com | (925) 518 6936 | Windows, patio, painters | Danville · Contra Costa County | — | — |
| Alan Carrillo Rios DBA Acr Roofing | Alan Alberto Carrillo Rios | — | (510) 427 0899 | Other roofers | Concord · Contra Costa County | — | — |
| Alan Clifford Soares DBA Western Mobile Service | Alan Clifford Soares | — | (925) 625 5199 | Other | Oakley · Contra Costa County | — | — |
| Alan Mckay Construction INC | Alan Roderick Mckay | alan@alanmckayconstruction.com | (925) 286 9026 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Alan Siding & Windows | Alan Siding & Windows | — | (925) 944 8762 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Alan Tamaev | Alan Tamaev | — | (815) 575 5916 | Other | Lafayette · Contra Costa County | — | — |
| Alan's Painting | Alan's Painting | — | (925) 687 6494 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Alania Construction | Dzhabiev Pavlik | — | (925) 260 9145 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Alansi's Plumbing INC | Yehia Kahtan Alansi | — | (415) 497 8700 | Other | Richmond · Contra Costa County | — | — |
| Alardima Roofing INC | Jose Alfonso Cordova Hernandez | — | (925) 628 9472 | Other roofers | Antioch · Contra Costa County | — | — |
| Alarm C C T V Edge | Gary Lynn Lawhon | — | (925) 639 6111 | Alarm and generators | Concord · Contra Costa County | — | — |
| Albert D Seeno Construction Co | Thomas Albert Seeno | — | (925) 671 7711 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Albert D Seeno Iii | Albert D Seeno Iii | — | (925) 682 6419 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Albert D Seeno Jr | Albert D Seeno Jr | — | (925) 671 7711 | HVAC | Concord · Contra Costa County | — | — |
| Albert's Tree Service | Zerimar Alvarado | — | (925) 446 5808 | Other | Concord · Contra Costa County | — | — |
| Alberto Navarro | Alberto Navarro | — | (510) 206 5517 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Alberto's Painting & Remodeling | Alberto's Painting & Remodeling | — | (510) 847 6469 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |