| Mori Plumbing | Mori Plumbing | — | (925) 303 8598 | Other | Brentwood · Contra Costa County | — | — |
| Morris Tile & Construction Co | Virgil Dee Jr Morris | — | (925) 963 2822 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Morrison Construction | Douglas Richard Morrison | — | (925) 354 8760 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Mortensen Roofing & Gutters INC | John William Mortensen | — | (925) 685 4613 | Other roofers | Concord · Contra Costa County | — | — |
| Mosher Consulting Services INC | John Harold Mosher | — | (408) 728 3689 | Other | Brentwood · Contra Costa County | — | — |
| Mosqueda Landscape | Mosqueda Landscape | — | (925) 628 2603 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Mostafa Bagheri | Mostafa Bagheri | info@mostafabagheri.com | (424) 347 4858 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Motif Home Design INC | Reza Alaey | hello@motifhd.com | (415) 604 7116 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Motown Mechanical | Motown Mechanical | info@motownmechanical.com | (510) 326 4030 | Other | Pinole · Contra Costa County | — | — |
| Motto Construction | Mundrucz Otto | mottoconstruction@gmail.com | (925) 457 2724 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Mount Diablo Fire LLC | Hector Jr Fernandez | — | (925) 699 9697 | Other | Concord · Contra Costa County | — | — |
| Mount Diablo Realty | Mount Diablo Realty | — | (925) 639-0361 | Property managers | Concord · Contra Costa County | — | — |
| Mount Verde Construction | Rosas-gonzalez Abel | — | (925) 207 7561 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Mountain Movers Excavation INC | Diana Roquemore | — | (510) 760 6992 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Mp Custom Metal | Mp Custom Metal | — | (925) 518 9465 | Other | Pacheco · Contra Costa County | — | — |
| Mp Electric And Lighting INC | Miguel Jr Perez | — | (925) 529 7308 | Electricians | Brentwood · Contra Costa County | — | — |
| Mpc General Construction | Michael Patrick Coakley | — | (925) 575 8883 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Mpm Bay Area Concrete | Mpm Bay Area Concrete | — | (925) 727 8382 | Other | Bay Point · Contra Costa County | — | — |
| Mr & Mrs Yacoub & Daughters INC | Anthony George Mogannam | — | (925) 854 2838 | Other | Danville · Contra Costa County | — | — |
| Mr Electric Of Concord Ca | Matthew Charles Spoonhour | — | (925) 246 5855 | Electricians | Concord · Contra Costa County | — | — |
| Mr Insulation INC | Nathan James Price | info@mrinsulation.com | (415) 492 1166 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Mr King Tut General Construction | Santos Alonso Tut-escobedo | — | (510) 860 9692 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Mr Landscaping | Mr Landscaping | — | (510) 478 4482 | Windows, patio, painters | Rodeo · Contra Costa County | — | — |
| Mr Painting | Mr Painting | — | (925) 752 8620 | Windows, patio, painters | Pittsburg · Contra Costa County | — | — |
| Mr Pavers Contractors Services INC | Gleyston Borges Soares | — | (510) 415 6198 | Windows, patio, painters | Rodeo · Contra Costa County | — | — |
| Mr Tree Specialist | Cesar Alejandro Padilla-Barreto | micah@micahrich.com | (707) 207 9480 | Tree | Richmond · Contra Costa County | — | — |
| Mr Z's Plumbing Experts | Tj Thomas Zamarripa | — | (925) 655 9285 | Other | Antioch · Contra Costa County | — | — |
| Mr. Poppy | Dustin James Miller | — | (408) 709 6455 | HVAC | Kensington · Contra Costa County | — | — |
| Mrcc Builder | Mrcc Builder | — | (925) 766 3713 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Mrm Construction | Armando Vicente Montalvo | — | (925) 768 9752 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Ms Glazing | Ms Glazing | — | (510) 759 9611 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Msb Property Management | Msb Property Management | — | (510) 649-3380 | Property managers | Walnut Creek · Contra Costa County | — | — |
| Mse Environmental INC | Martin Tecuanhuey | — | (925) 723 0300 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Msh Group | Mark Ross Howe | — | (510) 215 5134 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Msi Solutions INC | Carlos Rene Lopez De Leon | — | (415) 724 7046 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Mt Diablo Flooring Systems INC | Damian Christopher Jones | — | (925) 473 9500 | Other roofers | Pittsburg · Contra Costa County | — | — |
| Mt Diablo Gardening INC | Cesar Octavio Vera | — | (925) 240 9498 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Mt Diablo Lumber INC DBA C & J Fencing | Christopher Edward French | — | (925) 355 1380 | Windows, patio, painters | San Ramon · Contra Costa County | — | — |
| Mt Diablo Window Cleaning | Monica Iniguez | sales@mtdiablowindowcleaning.com | (925) 375 7948 | Other | Walnut Creek · Contra Costa County | — | — |
| Mt Fencing | Sammy Ariel Monterroso Zelaya | — | (925) 395 1878 | Other | Bay Point · Contra Costa County | — | — |