| Mohsen Shaban Esfahani | Mohsen Shaban Esfahani | — | (925) 360 8515 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Molina's Painting & Wallcovering INC | Vanessa Karina Molina | — | (925) 228 7487 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| Mondragon All Construction | Jaime Javier Mondragon Martinez | — | (925) 565 7469 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Monico Plumbing INC | Javier Mendoza | — | (925) 813 8917 | Other | Brentwood · Contra Costa County | — | — |
| Monroy Landscaping | Monroy Landscaping | — | (925) 207 5944 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Monster Home Inspection | Monster Home Inspection | — | (925) 775-5865 | Inspectors | Antioch · Contra Costa County | — | — |
| Monsuco | Cuarenta Ponce Esteban | contact@monsuco.com | (510) 942 9723 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Montair Electric LLC | Massinissa Berkenou | — | (415) 724 5348 | Electricians | Danville · Contra Costa County | — | — |
| Montano Construction | Erick Enrique Montano | montano@montanoconstruction.com | (925) 580 8408 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Montbay Construction Group INC | Alvarado Jose Saenz | — | (916) 870 6576 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Montclair Garden Company | John Whalen Vasquez | sebastian@aldusleaf.org | (510) 325 3612 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Monte Blanco General Construction INC | Elvis Israel Alvarado | — | (925) 354 9249 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Monterrosa Construction | Mauricio Alberto Monterrosa Reales | — | (510) 660 2250 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Montes Construction | Jose Natividad Montes | — | (415) 515 6035 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Montes Flooring | Montes Flooring | — | (925) 586 3085 | Other | Oakley · Contra Costa County | — | — |
| Montes Lathing & Plastering INC | Luis Alfonso Montes De Oca Cruz | — | (925) 852 9332 | Other | Concord · Contra Costa County | — | — |
| Montes Painting | Montes Painting | info@montespainting.com | (415) 722 1516 | Windows, patio, painters | Oakley · Contra Costa County | — | — |
| Montes Restoration Painting | Montes Restoration Painting | info@indiantypefoundry.com | (510) 367 8436 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Montes Tree Services | Leoncio Montes | — | (925) 325 2528 | Tree | Brentwood · Contra Costa County | — | — |
| Montesino Fire Protection Contractor | Montesino Fire Protection Contractor | — | (510) 621 4710 | Other | Richmond · Contra Costa County | — | — |
| Montesino Fire Protection Contractor INC | Ma Del Carmen Montesino Suarez | — | (510) 621 4710 | Other | Richmond · Contra Costa County | — | — |
| Montosa Construction | Anthony Ray Montosa | — | (925) 214 4195 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Montoya Construction | Buenaventura Toribio Montoya | — | (415) 850 0586 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Montoya Windows And Glass Doors | Montoya Windows And Glass Doors | — | (415) 412 6697 | Windows, patio, painters | Pleasant Hill · Contra Costa County | — | — |
| Montoya's Construction INC | Montoya Rodriguez Jesus | — | (925) 752 1668 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Monument Excavation | Monument Excavation | k.wemmer@monumentexcavation.com | (510) 406 4111 | Other | Martinez · Contra Costa County | — | — |
| Moonlite Electric | Richard Thomas Jr Brown | — | (510) 799 9473 | Electricians | Richmond · Contra Costa County | — | — |
| Moore Tile | Moore Tile | — | (925) 628 9865 | Other | Oakley · Contra Costa County | — | — |
| Moosechachos Electric | Ochoa Mora Alfonso | — | (925) 418 2296 | Electricians | Brentwood · Contra Costa County | — | — |
| Mor Construction INC | Jon Josef Mor | — | (925) 349 6582 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Mor Plumbing INC | Maricruz Morales | — | (760) 557 9941 | Other | Brentwood · Contra Costa County | — | — |
| Mora Concrete Design | Mora Concrete Design | — | (925) 470 8869 | Windows, patio, painters | Bay Point · Contra Costa County | — | — |
| Morales Home Improvements Co | Miguel Angel Morales Cruz | — | (925) 864 0134 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Morales Landscaping Premier | Daniel Gerardo Morales | moraleslandscapingpremier@gmail.com | (925) 586 1906 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| Morales Professional Construction INC | Norris Nelson Clawson | — | (925) 725 9540 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Moreno Tile Works INC | Alejandro Moreno | — | (925) 354 8165 | Other | Antioch · Contra Costa County | — | — |
| Morgan - Bonanno Development INC | Michael David Bonanno | — | (925) 820 2558 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| Morgan Electric INC | Michael Fred Matter | — | (925) 837 1957 | Electricians | San Ramon · Contra Costa County | — | — |
| Morgans Plumbing | Morgans Plumbing | — | (925) 812 0549 | Other | Martinez · Contra Costa County | — | — |
| Morgante Builders | Paul Gabriel Stenger Morgante | — | (510) 646 6884 | GC, remodel, ADU | Danville · Contra Costa County | — | — |