| A Ricky Roofing | Pablo Diego Sanchez | — | (408) 991 3363 | Other roofers | Hayward · Alameda County | — | — |
| A Rodriguez Electric | Alen Naun Rodriguez Flores | — | (415) 910 8529 | Electricians | Hayward · Alameda County | — | — |
| A S A P Construction | Julio Cesar Martinez | — | (415) 730 5997 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| A S A P Expert Plumbing & Construction | Lee Ka Kei | — | (415) 756 1889 | GC, remodel, ADU | Oakland · Alameda County | — | — |
| A S P Plumbing | A S P Plumbing | — | (650) 703 2006 | Other | Livermore · Alameda County | — | — |
| A S T Scaffolding | Jorge Miguel Avila | — | (669) 237 5456 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| A Sanchez Mechanical | A Sanchez Mechanical | — | (877) 359 1758 | HVAC | Fremont · Alameda County | — | — |
| A Siegfried Construction | Andrew Todd Siegfried | — | (925) 628 3282 | GC, remodel, ADU | Livermore · Alameda County | — | — |
| A T C Design Center INC | Amos Tamam | atcdesigncenter@gmail.com | (510) 945 0877 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| A T Concrete Services INC | Alexis Manuel Aceves Medina | — | (650) 385 1109 | Other | Hayward · Alameda County | — | — |
| A T M Construction | Ali Asghar Toraby-moghadam | — | (510) 435 5900 | Electricians | Berkeley · Alameda County | — | — |
| A T Weber Plumbing & Mechanical Services INC | Andrew Todd Weber | — | (510) 523 0628 | HVAC | Alameda · Alameda County | — | — |
| A Tamam Construction INC | Yossi Alkaslasi | — | (408) 478 3111 | GC, remodel, ADU | Fremont · Alameda County | — | — |
| A To Z Building & Flooring | Naim Mohammad Rahimi | — | (510) 785 1000 | GC, remodel, ADU | Hayward · Alameda County | — | — |
| A To Z Remodeling & Construction | Miguel Angel Salazar | — | (510) 557 5768 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| A V Electrical Solutions | Josue Salvador Alcantar | info@avelectricalsolutions.com | (619) 928 7092 | Electricians | San Leandro · Alameda County | — | — |
| A W Construction INC | Antoney Lap Wong | — | (510) 381 9963 | Electricians | Oakland · Alameda County | — | — |
| A Wire | A Wire | — | (510) 333 6756 | Electricians | Oakland · Alameda County | — | — |
| A Y Engineering | A Y Engineering | — | (510) 541 0868 | Other | Oakland · Alameda County | — | — |
| A&a Remodeling LLC | Francisco Javier Rodriguez Chavez | — | (510) 395 5077 | GC, remodel, ADU | San Leandro · Alameda County | — | — |
| A&e East Bay Interlocking Pavers INC | Garcia Del Real Adrian | — | (510) 300 7624 | Other | San Leandro · Alameda County | — | — |
| A&e Electrical Company INC | Steven Anthony Sievers | — | (650) 593 9111 | Electricians | Hayward · Alameda County | — | — |
| A&r Concrete | Ricardo Virgen | — | (505) 480 7725 | Other | Hayward · Alameda County | — | — |
| A&s Structural Force Co | Barajas Jorge Cisneros | — | (510) 634 6611 | Other | Newark · Alameda County | — | — |
| A+ Construction | Francisco Omar Arauz | — | (415) 323 8421 | GC, remodel, ADU | Berkeley · Alameda County | — | — |
| A+ Contractor INC | Odilon Nemesio Gonzalez | — | (510) 472 4589 | Other | San Leandro · Alameda County | — | — |
| A+ Quality Construction | Daniel Sarlea | — | (510) 754 8122 | GC, remodel, ADU | Dublin · Alameda County | — | — |
| A-1 American Plumbing Heating And Air Conditioning | David Michael Le May | — | (510) 581 0607 | HVAC | San Leandro · Alameda County | — | — |
| A-1 Bay Area Rooter & Plumbing | Matias Pablo Luis | — | (510) 712 0906 | Other | Oakland · Alameda County | — | — |
| A-1 Complete Yard Service LLC | Autar Singh Johal | — | (925) 829 9650 | Windows, patio, painters | Dublin · Alameda County | — | — |
| A-1 Contracting LLC | Robert Davis Piddock | — | (510) 928 0027 | Other | Castro Valley · Alameda County | — | — |
| A-1 Demolition & Hauling | Alvarez Francisco Alvarez | — | (510) 472 4844 | Other | Hayward · Alameda County | — | — |
| A-1 Electrical Services | Jeffrey Lee Moita | info@aelectricalservices.com | (510) 701 0240 | Electricians | Alameda · Alameda County | — | — |
| A-1 Glaswindor Industries INC | Jose Del Gallego Payawal | — | (408) 263 8791 | Windows, patio, painters | Fremont · Alameda County | — | — |
| A-1 Modular INC | Jose Salvador Ramirez | marketing@a-modular.com | (510) 999 7721 | Electricians | San Leandro · Alameda County | — | — |
| A-1 Septic Tank Service INC | Sarah Nicole Cortez | — | (510) 886 4455 | Other | Hayward · Alameda County | — | — |
| A-1 Services Electrical - Stucco | Jose Mauricio Diaz | — | (510) 274 3060 | Electricians | Hayward · Alameda County | — | — |
| A-z Commercial And Residential Electrical | Cilliers Barry | — | (510) 917 1192 | Electricians | Hayward · Alameda County | — | — |
| A-z Restoration INC | Tamir Avi Levi | — | (818) 983 4087 | GC, remodel, ADU | Castro Valley · Alameda County | — | — |
| A/c Guys Cooling And Heating INC | Ulises Alcantara | — | (925) 596 8888 | HVAC | Pleasanton · Alameda County | — | — |