| Luxe Construction | Barrera Cruz Aguilar Micdael | — | (707) 364 6546 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Luxury Construction LLC | Miguel Angel Santiago | luxuryconstruction77@gmail.com | (650) 455 9537 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Luxury Home Renovations INC | Vidal Pompilio Hernandez Fernandez | — | (408) 903 0391 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Lv Masonry INC | Vicente Estrada Vera | bids05@lvmasonry.com | (510) 640 3131 | Other | Oakley · Contra Costa County | — | — |
| Lv Yard Maintenance | Lv Yard Maintenance | — | (925) 848 7717 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Lve Construction INC DBA Stucco King | Vando Marino Estrela | — | (707) 446 6660 | Other | Brentwood · Contra Costa County | — | — |
| Lyco Construction INC | Morgan Nathaniel Lyons | — | (415) 726 8838 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Lynn Safety INC | Steven Patrick Lynn | — | (925) 438-0621 | Other | Concord · Contra Costa County | — | — |
| Lyons Builders INC | Daniel Anthony Lyons | — | (925) 284 1806 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| M & L Construction Services | Michael Charles Morris | — | (925) 964 3118 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M & L Overhead Doors | M & L Overhead Doors | — | (925) 260 5662 | Other | Antioch · Contra Costa County | — | — |
| M & M Construction | Vaezinia Massoud | — | (510) 334 6106 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| M & M Construction & Home Design | Hen Sheli | — | (888) 973 7366 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M & M Electric | Marcus James Jr Mc Intosh | — | (925) 418 4761 | Electricians | Brentwood · Contra Costa County | — | — |
| M & M Home Improvement INC DBA Elegant Door & Sashes | Matthew Scott Boozer | — | (925) 829 7473 | Other | Walnut Creek · Contra Costa County | — | — |
| M & M Plumbing | M & M Plumbing | — | (415) 720 4511 | Other | Pinole · Contra Costa County | — | — |
| M & M Property Management | M & M Property Management | — | (925) 798-5550 | Property managers | Concord · Contra Costa County | — | — |
| M & M Tree Service | Mark Charles Menges | — | (510) 237 5618 | Tree | Point Richmond · Contra Costa County | — | — |
| M & S Hvacr Contractors INC | Alfredo Roger Valderrama | — | (415) 730 3444 | HVAC | Concord · Contra Costa County | — | — |
| M - Core Construction | Joseph Alfonso Maruri | — | (925) 270 7765 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M A Bergesen Contractor & Builder | Morris Arnold Bergesen | — | (925) 997 5325 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| M B Electric | Mark Christopher Bellis | info@mbelectric.com | (925) 783 0820 | Electricians | Oakley · Contra Costa County | — | — |
| M Benshoof Construction Co | Mark David Benshoof | — | (510) 773 2665 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| M C Construction | Michael Thomas Cummins | — | (925) 963 5249 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| M C K Services INC | David Allen Ii Praklet | — | (925) 957 9200 | Other | Concord · Contra Costa County | — | — |
| M C Plumbing | M C Plumbing | — | (925) 628 7622 | Other | Pittsburg · Contra Costa County | — | — |
| M D Construction | Marc Talastas Del Rosario | — | (510) 953 3188 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M D I Builders | M D I Builders | — | (510) 610 3347 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| M D R Electric | Matthew David Raver | — | (925) 383 9899 | Electricians | Crockett · Contra Costa County | — | — |
| M D Tree Service | Melvin Omar Guardado | — | (925) 597 7355 | Other | Bay Point · Contra Costa County | — | — |
| M D Two | M D Two | — | (925) 323 7346 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| M E C Construction | Mark Earnest Crowe | — | (925) 356 2364 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| M E M Engineering | M E M Engineering | — | (925) 674 9082 | Other | Walnut Creek · Contra Costa County | — | — |
| M Elera Electric | Miguel Angel Elera | — | (925) 550 1870 | Electricians | Brentwood · Contra Costa County | — | — |
| M F Sanchez Construction & Painting | Marcelo Flores Sanchez | marcelosanchez@constrpainting.com | (510) 502 7074 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| M Flores Construction | Michael Samuel Flores | — | (415) 312 3801 | GC, remodel, ADU | Rodeo · Contra Costa County | — | — |
| M Fulton Painting | M Fulton Painting | fultonpainting@sbcglobal.net | (925) 957 0146 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| M G Bay Area Construction | Marian Victor Gheorghe | mgbaconstr@gmail.com | (510) 825 8548 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| M G Construction | Matthew Clinton Green | info@mgconstruction.com | (925) 354 6123 | GC, remodel, ADU | Discovery Bay · Contra Costa County | — | — |
| M G Construction | Miguel Angel Gonzalez Sanchez | info@mgconstruction.com | (510) 334 8436 | GC, remodel, ADU | Rodeo · Contra Costa County | — | — |