| M3 Electrical INC | Michael Mark Iii Meyokovich | info@m3-electrical.com | (925) 789 9177 | Electricians | Discovery Bay · Contra Costa County | — | — |
| Mab Building Solutions INC | Michael Alan Borders | — | (925) 628 7781 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Mab Enterprises | Michael Alan Borders | — | (925) 706 0106 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Mac Construction Group INC | Mauricio Alves Chagas | — | (510) 439 8667 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Mac Plumbing | Mac Plumbing | — | (510) 207 2782 | Other | Danville · Contra Costa County | — | — |
| Mace Electric | Paul Joseph Mason | — | (510) 410 9077 | Electricians | Clayton · Contra Costa County | — | — |
| Mack Shemirani | Mack Shemirani | — | (510) 329 6959 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Mackenzie Construction Services INC | John Waite Mackenzie | — | (510) 367 6098 | GC, remodel, ADU | Port Costa · Contra Costa County | — | — |
| Mad Creations Interior Faux Paint & Design | Stacie Marguerite Spurrier | — | (510) 455 0596 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Mad Dog Construction | Robert Steven Bilyeu | — | (925) 876 5508 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Mad Pelican Roofing LLC | David Alexander Metrock | — | (925) 818 1588 | Other roofers | Concord · Contra Costa County | — | — |
| Madden Engineering | Alan Matthew Madden | — | (925) 507 6083 | Other | Concord · Contra Costa County | — | — |
| Madison Gomas Construction | Madison Edward Gomas | — | (925) 409 0798 | GC, remodel, ADU | Bethel Island · Contra Costa County | — | — |
| Madison Park Financial Corporation | John Protopappas | — | (510) 452 2944 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Madrid Construction | Jose Luis Madrid | madridconstru@gmail.com | (510) 375 9349 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Madsa Development | Miguel Madrid | — | (844) 623 7226 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Magana's Star Painting | Magana's Star Painting | — | (925) 727 5848 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Mageney Constructors | Mageney Constructors | — | (925) 382 9201 | Other | Alamo · Contra Costa County | — | — |
| Magic Brush Painting INC | Chin Haeng Cho | — | (510) 758 9364 | Windows, patio, painters | Pinole · Contra Costa County | — | — |
| Magic Hammer Remodeling | Magic Hammer Remodeling | — | (925) 673 0949 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Magic View Landscaping | Garcia Adrian Jimenez | — | (925) 727 1678 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Magna Construction INC | Oscar Gerardo Hernandez | — | (707) 980 9830 | Other | Discovery Bay · Contra Costa County | — | — |
| Magnabuild LLC | Anahat Singh | general@magnabuild.co.uk | (510) 447 9353 | GC, remodel, ADU | Hercules · Contra Costa County | — | — |
| Magnificent Plumbing & Rooter INC | Rene Galicia-Xochitemol | — | (925) 478 8073 | Other | San Ramon · Contra Costa County | — | — |
| Magnis Builder LLC | Mirloo Hooman | — | (650) 422 0804 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Magnus Ericsson Construction | Magnus Fred Ericsson | — | (925) 785 4867 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Maida Construction Company | Frederick Charles Maida | — | (925) 228 3837 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Maiden Custom Floors | Maiden Custom Floors | — | (415) 410 6294 | Other | Richmond · Contra Costa County | — | — |
| Maiden Lane Builders LLC | William Kenneth Zehringer | — | (510) 994 8797 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Main Electric INC | Nelson Quinones Revocal | — | (415) 726 2467 | Electricians | Hercules · Contra Costa County | — | — |
| Mainline Builders INC | Michael Christopher Robinson | — | (925) 787 4276 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Maison Du Charme | Maison Du Charme | tom@maisonducharme.com | (925) 788 4292 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Majestic Construction | David Alexander Hajostek | — | (925) 488 3494 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Majestic Design INC | Waleed Naji Jweainat | — | (415) 235 9307 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Majestic Electric | Norman Lawrence De Soto | — | (925) 207 0532 | Electricians | Concord · Contra Costa County | — | — |
| Majestic Floors INC | Vincent Lee Steele | — | (925) 825 0771 | Other | Concord · Contra Costa County | — | — |
| Majestic Landscape | Majestic Landscape | majesticpool@aol.com | (925) 676 1545 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Majestic Landscape Construction | Mario Alberto Solis Contreras | — | (925) 207 3060 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Majestic Mechanical | Majestic Mechanical | 391-4528info@majesticmechanical.com | (925) 658 2126 | HVAC | Antioch · Contra Costa County | — | — |
| Majestic Property Services | Ortega David | — | (925) 783 1181 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |