| Master Builders Of California | Master Builders Of California | — | (925) 642 0978 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Master Craftsman And Carpentry INC | David Joseph Martinez | — | (925) 357 8935 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Master Of Tankless Water Heaters | Master Of Tankless Water Heaters | — | (541) 633 0667 | Other | San Ramon · Contra Costa County | — | — |
| Master Of The Fixes INC | Andres Miguel Medina Duque | — | (925) 497 7280 | GC, remodel, ADU | Bay Point · Contra Costa County | — | — |
| Master Painting Services INC | Camacho Arroyo Francisco | masterjo376@gmail.com | (408) 841 2110 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Mastercraft Custom Engineering | Mastercraft Custom Engineering | — | (408) 600 8513 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Masterful Builder | Masterful Builder | — | (925) 388 3284 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Masterful Builder INC | Kostiantyn Shkolnyi | — | (925) 388 3284 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Masterpiece Steel Stud Systems | Masterpiece Steel Stud Systems | — | (510) 377 7511 | Other | Oakley · Contra Costa County | — | — |
| Masters Builder | Masters Builder | — | (925) 785 0149 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Masterworks | Robert John Murray | — | (510) 469 8846 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Mastic Master | Mastic Master | info@masticmaster.com | (925) 383 5998 | Other | Knightsen · Contra Costa County | — | — |
| Mat Boustead Construction | Mathew Richard Boustead | — | (925) 300 6232 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Matalon S F INC DBA Creation 7 Builders | Eyal Matalon | — | (415) 860 7817 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Matamoros Welding | Matamoros Welding | — | (925) 625 1100 | Other | Oakley · Contra Costa County | — | — |
| Material Handling & Storage INC | Miley Scott| Harms Scott Harms | — | (510) 409 1989 | Other | Danville · Contra Costa County | — | — |
| Matheneys Plumbing & Heating | Matheneys Plumbing & Heating | — | (925) 362 9814 | HVAC | Danville · Contra Costa County | — | — |
| Mathers Tree Service LLC | Richard Roy Mathers | — | (925) 372 3649 | Tree | Pleasant Hill · Contra Costa County | — | — |
| Matrix Hg INC | Daniel Bryan Greeson | — | (925) 459 9200 | HVAC | Concord · Contra Costa County | — | — |
| Matt Sayles Construction | Matthew Cole Sayles | — | (510) 333 5698 | GC, remodel, ADU | Kensington · Contra Costa County | — | — |
| Matt Wilson Electric | Matthew Ryan Wilson | — | (510) 417 1203 | Electricians | El Sobrante · Contra Costa County | — | — |
| Mattei Construction Services INC | Richard Michel Mattei | — | (925) 339 3280 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Matthew Dashner Construction | Matthew Dale Dashner | — | (925) 876 9137 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Matthew Engle Construction INC | Engle Matthew | — | (415) 265 7439 | GC, remodel, ADU | Moraga · Contra Costa County | — | — |
| Matthew F Fahy Construction | Matthew Francis Fahy | — | (925) 348 2808 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Matthew Holland Charlot | Matthew Holland Charlot | — | (510) 919 5354 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Matthew M Walburger | Matthew M Walburger | — | (510) 220 2000 | HVAC | Martinez · Contra Costa County | — | — |
| Matthew P Whalley | Matthew P Whalley | — | (925) 366 6199 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Matthew Rapa | Matthew Rapa | — | (415) 827 4884 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Matthew's A A A INC | J Guadalupe Dorado | — | (925) 207 9171 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Mattson Plumbing Company | Russell Jon Mattson | — | (925) 247 4902 | Other | Discovery Bay · Contra Costa County | — | — |
| Mauri Concrete Construction Company INC | Marcelo Daniel Mauri | — | (510) 541 5260 | Other | El Sobrante · Contra Costa County | — | — |
| Mauro's Plumbing INC | Mauro Ferreira Martins | — | (510) 290 2785 | Other | El Cerrito · Contra Costa County | — | — |
| Maverick's General Engineering | Maverick's General Engineering | — | (925) 329 2116 | Other | Concord · Contra Costa County | — | — |
| Max's Painting | Thomas Jude Max | — | (925) 753 0974 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Maxwell D Samson Construction | Maxwell Daniel Samson | — | (925) 548 5703 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Mayactivated INC | Meital Hasson | — | (323) 605 6471 | Other | Pittsburg · Contra Costa County | — | — |
| Mayan Builders Corp | Oscar Homero Cac Cucul | — | (925) 297 7262 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Maz Construction | Mohammadali Zarei | — | (925) 890 6033 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Mazariegos Builder | Mazariegos Builder | — | (415) 412 7944 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |