| All Trades Co-op | Robert Dyke Pipkins | — | (925) 584 9128 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| All Trades Construction Services INC | Robert Dyke Pipkins | — | (925) 584 9128 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| All Volts Support INC | Ali Salamat | — | (415) 349 1176 | Electricians | Concord · Contra Costa County | — | — |
| All Wall Company | Maciel Mario | — | (925) 518 7269 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| All Water Heaters & Plumbing LLC | David Jason Ballard | — | (925) 301 7890 | Other | Concord · Contra Costa County | — | — |
| All West Company | Nam Hoai Trinh | — | (925) 408 0257 | Electricians | Pacheco · Contra Costa County | — | — |
| All-american Electric-contr | Randall Lyle Zierau | — | (510) 410 4110 | Electricians | Byron · Contra Costa County | — | — |
| All-bay Refrigeration | All-bay Refrigeration | — | (510) 758 1406 | HVAC | El Sobrante · Contra Costa County | — | — |
| All-cal Electric | Jose Elias Jaime-rangel | — | (925) 234 1563 | Electricians | Antioch · Contra Costa County | — | — |
| All-pro Roofing Company | Steven Ray Hubbard | — | (925) 825 4470 | Other roofers | Lafayette · Contra Costa County | — | — |
| Allan D Daniel Construction | Allan Dale Daniel | — | (925) 260 3354 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Allan Rixford Construction | Allan Edward Rixford | — | (510) 334 3896 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Allcom Electronic Systems Company INC | Russell Kent Van Emmerik | — | (925) 513 0393 | Other | Discovery Bay · Contra Costa County | — | — |
| Allen Co Construction | Kyle James Allen | — | (925) 878 1247 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Allen Construction | Allen A Dadafarin | — | (925) 212 8123 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Alley Electric | Wesley John Sedain | alleyelectric@comcast.net | (510) 573 0427 | Electricians | Lafayette · Contra Costa County | — | — |
| Alliance Plastering Services | Vera Perez Rafael | — | (925) 771 0434 | Other | Antioch · Contra Costa County | — | — |
| Alliance Plastering Services INC | Perez Rafael Vera | — | (925) 771 0434 | Other | Antioch · Contra Costa County | — | — |
| Alliatza Flooring INC | Carlos Eduardo Meza Diarte | — | (510) 932 0307 | Other | Richmond · Contra Costa County | — | — |
| Allied Demolition Services INC | Matthew Jason Lipelt | — | (925) 705 0192 | Other | Walnut Creek · Contra Costa County | — | — |
| Allied Propane Service INC | Dustin Michael Kaiser | webalerts@warmthoughts.com | (510) 237 7077 | Other | Richmond · Contra Costa County | — | — |
| Allied Propane Transportation INC | Dustin Michael Kaiser | — | (510) 237 7077 | Other | Richmond · Contra Costa County | — | — |
| Allied Restoration Company | Allied Restoration Company | — | (925) 722-6594 | Restoration | Walnut Creek · Contra Costa County | — | — |
| Allied Universal® Security Services | Allied Universal® Security Services | — | (510) 839-4041 | Alarm and generators | Concord · Contra Costa County | — | — |
| Allitech Services | Darrin Blaine Allison | — | (925) 518 8180 | Electricians | Oakley · Contra Costa County | — | — |
| Allstar Electric Construction Services INC | Ashlie Anne Pantell | — | (925) 349 6208 | Electricians | Concord · Contra Costa County | — | — |
| Allstar Floor Covering | Daniel Raymond Box | — | (925) 260 6671 | Other | Bethel Island · Contra Costa County | — | — |
| Alltek Restoration INC | Andrew Christopher Easton | — | (925) 732 7200 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Allways Painting | Allways Painting | — | (925) 787 6109 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Ally Electric | Saglam Metin | — | (510) 559 7700 | Electricians | Richmond · Contra Costa County | — | — |
| Almaden Pool Services | Rajwant Singh Samra | %20almadenpoolsrvcs@sbcglobal.net | (510) 386 3892 | Pool | San Ramon · Contra Costa County | — | — |
| Almighty Plumbing | Michael Fermin Penate | — | (925) 318 4448 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Aloha Concrete And Design | Fangaiuiha Masiata Lavaka | — | (925) 334 8331 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Aloha Pool Service | Sean Kealii Cordeiro | — | (925) 240 7117 | Pool | Brentwood · Contra Costa County | — | — |
| Alonso Painting | Alonso Edilberto Hernandez | — | (415) 377 8908 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Alonso Zambrano Painting | Alonso Zambrano Painting | — | (415) 640 0053 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| Alonzo Mcshane Construction | Allen Eugene Jr Mcshane | — | (510) 735 1905 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Alp Construction & Painting INC | Adrian Lopez Perez | — | (925) 567 4777 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Alpha & Beta Electric LLC | Bernardo Gonzalez | — | (925) 219 6053 | Electricians | Pittsburg · Contra Costa County | — | — |
| Alpha Concrete Pumping | Alpha Concrete Pumping | — | (925) 864 4405 | Other | Brentwood · Contra Costa County | — | — |