| #1 Acoustics | Candice Diane Hanisch | — | (510) 489 2985 | Other | Hayward · Alameda County | — | — |
| 360 Degrees Concrete INC | Alejandre Adrian Rodriguez | impallari@gmail.com | (209) 321 6889 | Other | Fremont · Alameda County | — | — |
| 3D Signs LLC | Keping Jiang | — | (510) 918 8129 | Other | San Leandro · Alameda County | — | — |
| 3D Studio INC DBA Joseph Farais | Joseph Patrick Farais | — | (510) 220 0220 | Other | Oakland · Alameda County | — | — |
| 911 Garage Doors | 911 Garage Doors | — | (510) 292 1644 | Other | Hayward · Alameda County | — | — |
| A & A Door Repair INC | Armando Guillen-Magana | aadoorrepairinc@gmail.com | (510) 681 5535 | Other | Newark · Alameda County | — | — |
| A & B Plumbing & Backflow | Michael Anthony Branco | — | (510) 471 4282 | Other | Hayward · Alameda County | — | — |
| A & K Underground | A & K Underground | — | (650) 222 4058 | Other | Newark · Alameda County | — | — |
| A & M Lath & Plastering INC | Moises Meza Gastelum | — | (510) 332 7629 | Other | Hayward · Alameda County | — | — |
| A & S Garage Door Services | Christopher Lawrence Wolosz | — | (510) 489 3189 | Other | Hayward · Alameda County | — | — |
| A & V Drywall | A & V Drywall | — | (510) 815 3288 | Other | Alameda · Alameda County | — | — |
| A + Wood Flooring Solution | A + Wood Flooring Solution | — | (510) 759 5466 | Other | San Leandro · Alameda County | — | — |
| A A Johnson & Son INC | Lawrence Neldam Twomey | — | (510) 658 9796 | Other | Oakland · Alameda County | — | — |
| A A Office Equipment Co INC | John Charles Procita | — | (510) 782 6110 | Other | Hayward · Alameda County | — | — |
| A B C Flooring | A B C Flooring | — | (650) 518 1674 | Other | Oakland · Alameda County | — | — |
| A B Plumbing | A B Plumbing | — | (415) 333 5566 | Other | Oakland · Alameda County | — | — |
| A Better Rooter Plumbing & Engineering INC | Jacques Michel Etienne | — | (510) 527 1219 | Other | Berkeley · Alameda County | — | — |
| A C Garage Doors | A C Garage Doors | — | (408) 857 8355 | Other | Newark · Alameda County | — | — |
| A Cut Above Wallcovering | A Cut Above Wallcovering | — | (925) 519 2319 | Other | Pleasanton · Alameda County | — | — |
| A D R Fire Protection | A D R Fire Protection | — | (510) 750 3909 | Other | Union City · Alameda County | — | — |
| A G M Artistic Signs | A G M Artistic Signs | — | (925) 833 7446 | Other | Livermore · Alameda County | — | — |
| A G Natural Stone | A G Natural Stone | — | (510) 887 8359 | Other | Hayward · Alameda County | — | — |
| A Good Plumber INC | Gary Alfred Confenti | — | (510) 376 9098 | Other | Livermore · Alameda County | — | — |
| A M S Proper Floors INC | Jose Mauricio Alba Garibay | — | (510) 825 1587 | Other | Hayward · Alameda County | — | — |
| A P Concrete | A P Concrete | apcjohn24@gmail.com | (925) 449 6706 | Other | Livermore · Alameda County | — | — |
| A R P Hardscape INC | Paniagua Alejandro Ramirez | — | (925) 208 9916 | Other | San Leandro · Alameda County | — | — |
| A S P Plumbing | A S P Plumbing | — | (650) 703 2006 | Other | Livermore · Alameda County | — | — |
| A T Concrete Services INC | Alexis Manuel Aceves Medina | — | (650) 385 1109 | Other | Hayward · Alameda County | — | — |
| A Y Engineering | A Y Engineering | — | (510) 541 0868 | Other | Oakland · Alameda County | — | — |
| A&e East Bay Interlocking Pavers INC | Garcia Del Real Adrian | — | (510) 300 7624 | Other | San Leandro · 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+ Contractor INC | Odilon Nemesio Gonzalez | — | (510) 472 4589 | Other | San Leandro · Alameda County | — | — |
| A-1 Bay Area Rooter & Plumbing | Matias Pablo Luis | — | (510) 712 0906 | Other | Oakland · 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 Septic Tank Service INC | Sarah Nicole Cortez | — | (510) 886 4455 | Other | Hayward · Alameda County | — | — |
| Aaa Fire Protection Services | Brent Hathaway Patterson | — | (800) 543 5556 | Other | Union City · Alameda County | — | — |
| Aall Fire Protection Services | Edward Raymond Gonsalves | — | (888) 988 0202 | Other | Livermore · Alameda County | — | — |
| Abante Rooter And Plumbing INC | Fred Ramezan Heidarpour | — | (510) 534 1636 | Other | Emeryville · Alameda County | — | — |