| Majic Landscape | Majic Landscape | — | (925) 818 0531 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Majid Construction | Kolahdooz Majid | — | (510) 331 4184 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Malachi Plumbing INC | Alvarado Hugo Ramirez | malachiplumbing77@gmail.com | (925) 726 7460 | Other | Oakley · Contra Costa County | — | — |
| Malaeb Construction INC | Ashraf Adam Malaeb | adam@malaebconstruction.com | (510) 449 8185 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Malagic Construction INC | Malagic Misver | — | (415) 847 9613 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Malino Refrigeration LLC | Gregory Mark Guastavino | — | (650) 554 8124 | HVAC | Danville · Contra Costa County | — | — |
| Malley Construction | Michael Patrick Malley | — | (925) 994 7218 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Man Tat Szeto | Man Tat Szeto | — | (510) 703 7900 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Man-fer-construction | Manuel De Jesus Fernandez Benitez | — | (925) 695 4666 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Manage Build INC | Ehsan Majdzaringhalam | — | (925) 640 3089 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Management Design V Brothers Corp | Jose Federico Ventura | — | (510) 672 1899 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Mancon Building Corp | Steven Gary Mangels | — | (925) 831 2896 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Manhattan Builders | Manhattan Builders | — | (925) 917 0050 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Manny's Handyman Services | Manuel Antonio Castaneda | — | (415) 686 1465 | GC, remodel, ADU | Hercules · Contra Costa County | — | — |
| Manuel Garcia Construction Solutions | Manuel Aniceto Jr Garcia | — | (925) 360 5913 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Manuel Iglesias Concrete INC | Iglesias Manuel | manuelconcrete@gmail.com | (925) 437-0943 | Other | Oakley · Contra Costa County | — | — |
| Manuel Pastor Forever Tile | Manuel Pastor Forever Tile | — | (510) 230 6990 | Other | Rodeo · Contra Costa County | — | — |
| Mara Construction | Anthony Michael Maramonte | — | (510) 385 8251 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Maravilla's Paver Systems | Maravilla's Paver Systems | — | (925) 348 1460 | Other | Antioch · Contra Costa County | — | — |
| Marble System Installation INC | Jerzy Szczerban | — | (415) 205 8860 | Other | Concord · Contra Costa County | — | — |
| Marc Croke Electric | Marc Thomas Croke | — | (925) 639 4474 | Electricians | Pleasant Hill · Contra Costa County | — | — |
| Marc Lee Silvani | Marc Lee Silvani | — | (925) 408 7226 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Marchio Construction | Raymond Richard Marchio | — | (925) 727 7083 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Marciniak Construction | Edward Robert Marciniak | — | (510) 432 3046 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Marco's Floor Covering | Marco's Floor Covering | — | (415) 261 3534 | Other | San Pablo · Contra Costa County | — | — |
| Marcom Innovations Contracting | Mark Eugene Hernandez | — | (925) 768 2306 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Marconis Construction & Electric INC | Hassan Mirzai | — | (510) 730 6717 | Electricians | Lafayette · Contra Costa County | — | — |
| Marcus J Madrid INC DBA Guaranteed Plumbing | Marcus John Madrid | — | (925) 820 2090 | Other | Lafayette · Contra Costa County | — | — |
| Mares & Dow Construction & Skylights INC | Archie Ray Mares | — | (925) 671 9500 | Electricians | Concord · Contra Costa County | — | — |
| Marina Continental Light And Shade INC | Benedict Robert Jr Galik | — | (510) 215 9600 | HVAC | El Cerrito · Contra Costa County | — | — |
| Marine & Industrial Services INC | Sharon Keaton Hannaford | — | (925) 757 8791 | HVAC | Antioch · Contra Costa County | — | — |
| Marino Electric | Ryan Carl Marino | — | (925) 488 7014 | Electricians | Oakley · Contra Costa County | — | — |
| Mario Mazzamuto Construction | James Salvatore Mazzamuto | — | (925) 228 7376 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Mario Navea General Building Contractor | Mario Navea General Building Contractor | — | (510) 734 9780 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Mario Velasco | Mario Velasco | — | (925) 757 9192 | Electricians | Antioch · Contra Costa County | — | — |
| Marius Construction | Adamache Marius | — | (510) 828 6551 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Mark Allen Linden | Mark Allen Linden | — | (925) 876 0104 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Mark Anastas Floor Service | Mark David Anastas | — | (925) 664 7750 | Windows, patio, painters | Bay Point · Contra Costa County | — | — |
| Mark Andrew Homes | Mark Andrew Homes | — | (925) 389 7885 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Mark Bellingham Painting INC | Bellingham Mark | — | (925) 247 0092 | Windows, patio, painters | Lafayette · Contra Costa County | — | — |