| M G Construction | Golfran Eulalio Morales | info@mgconstruction.com | (415) 410 9713 | Electricians | Richmond · Contra Costa County | — | — |
| M G Home Renovations | M G Home Renovations | — | (510) 529 1636 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M G M's Cabinet Installation Service | Michael Gordon Moxley | — | (510) 334 1781 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| M G Painting | M G Painting | — | (415) 336 5412 | Windows, patio, painters | Hercules · Contra Costa County | — | — |
| M G R General Const & C-8 | Manuel Gregorio Reyes | — | (925) 705 0205 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| M I C Electric INC | Michael James Micheletti | — | (510) 755 3812 | Electricians | Walnut Creek · Contra Costa County | — | — |
| M J Construction | Hector Miguel Jerez | — | (510) 847 0652 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| M J Hayhurst Const Co | Michael-joe Matt Hayhurst | — | (510) 847 0619 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| M J M Construction | Matthew Jacob Miller | — | (925) 250 3837 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| M J Modern Stairways | Jabri Mehdi | — | (510) 365 9451 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M J R Residential Remodeling | M J R Residential Remodeling | — | (925) 890 2165 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M Jones Construction INC | Michael Edward Owen Jones | — | (925) 639 0733 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M K Construction | Matias Nicolas Keil | — | (510) 545 6116 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| M L Construction | Lopez Martin | hello@mlconstruction.com | (925) 525 1637 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| M Lane Construction | Michael James Lane | — | (925) 849 6358 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| M M Electrical | Juan Ramon Aguero | — | (504) 390 9587 | Electricians | Oakley · Contra Costa County | — | — |
| M N Construction | Noori Mahmood | — | (925) 234 0835 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| M P Plumbing | M P Plumbing | — | (925) 381 9435 | Other | Clayton · Contra Costa County | — | — |
| M R General Contractor | M R General Contractor | — | (415) 786 7549 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M R O Construction | Mario Rodolfo Orozco | — | (510) 220 6095 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| M R Sereda Co | Sereda Marian | — | (510) 407 3145 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| M Ringhofer Construction | Mathew Frank Ringhofer | — | (925) 787 1534 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| M S Custom Painting | Marco Antonio De Santiago | — | (510) 383 0105 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| M S K Design Build INC | Scott Jonathan Westby | — | (925) 944 0153 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M T B Electric | Jules-michael Zackiel Bozajeski | — | (415) 855 5126 | Electricians | Concord · Contra Costa County | — | — |
| M T D INC | Timothy John Tobin | — | (925) 944 0661 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M T Z Electric INC | Jesse Daniel Coward | info@mtzelectric.com | (703) 819-9486 | Electricians | Martinez · Contra Costa County | — | — |
| M V M Electric | Michael John Mathers | — | (925) 998 7271 | Electricians | Walnut Creek · Contra Costa County | — | — |
| M V P Construction LLC | Michael Anthony Vila | — | (925) 586 1478 | GC, remodel, ADU | Pacheco · Contra Costa County | — | — |
| M V Power Construction INC | Manuel Salvator Vierra | — | (925) 634 5426 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| M&j Prime Builders | Reyes Javier Ochoa | — | (510) 837 0451 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| M&m Carpet Service | Matthew Byron Porter | — | (562) 787 9771 | Other | San Ramon · Contra Costa County | — | — |
| M&m Elite Flooring INC | Panuco Manuel Ayala | manuel@mmeliteflooring.com | (510) 703 9803 | Other | San Pablo · Contra Costa County | — | — |
| M&n Enterprises INC DBA Nancy's Plumbing | Marlon Osvaldo Orellana | — | (925) 350 0182 | Other | Antioch · Contra Costa County | — | — |
| M&r Home Builders | Matan Shuker | — | (510) 220 1527 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M&t New Bay Builders INC | Francisco Javier Morales Barrios | — | (510) 680 6649 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| M-23 Mechanical Systems | Edmund Siu Yin Chan | — | (925) 730 9020 | HVAC | Danville · Contra Costa County | — | — |
| M.garcia's Concrete Service INC | Luis Humberto Lara | — | (925) 383 0237 | Other | Antioch · Contra Costa County | — | — |
| M.r.landscaping INC | Erick Neftaly Valdez Reyes | — | (925) 771 9126 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| M2 Engineering LLC | Marcelo Tavares Goncalves | — | (415) 374 3356 | Other | Richmond · Contra Costa County | — | — |