| Mtz Brothers Tile INC | Daniel Martinez-Navarro | — | (408) 797 7060 | Other | Antioch · Contra Costa County | — | — |
| Mtz Landscape & Design LLC | Luis Angel Martinez Cano | — | (650) 208 5927 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Mtz Pro Plumbing | Mtz Pro Plumbing | — | (925) 222 7318 | Other | Bay Point · Contra Costa County | — | — |
| Mud Worx INC | Rivera Natalia Perez | — | (510) 980 2117 | Other | Antioch · Contra Costa County | — | — |
| Mueller Construction Corp | Zack Ryan Mueller | — | (415) 744 4394 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Mugi's Hardwood Floors | Mugi's Hardwood Floors | — | (510) 333 1190 | Other | El Cerrito · Contra Costa County | — | — |
| Multitude Private Security | Multitude Private Security | info@multitudexpro.com | (925) 536-1641 | Alarm and generators | Pleasant Hill · Contra Costa County | — | — |
| Mundial | Robert Andrew Meade | — | (510) 384 7467 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Murguia Construction | Victor Manuel Murguia Bonilla | murguiaconstruction2001@gmail.com | (925) 565 9561 | GC, remodel, ADU | Pittsburg · Contra Costa County | — | — |
| Murillo Construction & Painting & Remodeling | Joel Sr Murillo | — | (510) 660 9596 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Murillo Landscape Maintenance | Murillo Landscape Maintenance | — | (925) 684 0606 | Windows, patio, painters | Bethel Island · Contra Costa County | — | — |
| Muro's Construction INC | Araceli Ramirez | editorial@murosconstruction.com | (925) 752 8435 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Murphy Flooring INC | Cathleen Marie Jochum | — | (925) 328 9425 | Other | Concord · Contra Costa County | — | — |
| Murphymckenna Construction | Sean Patrick Mc Kenna | — | (510) 778 9964 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Murray D Buys Construction | Murray David Buys | — | (530) 632 1248 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Mvc Electric INC | Jimy Hendry Vega-garcia | — | (415) 570 1987 | Electricians | Bay Point · Contra Costa County | — | — |
| Mvt Construction | Juan Manuel Valverde De La Torre | — | (925) 421 4107 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Mw Masonry | Mw Masonry | — | (925) 595 5690 | Other | Antioch · Contra Costa County | — | — |
| Mxdi Builder Company | Emmanuel Alejandro Rojas | info@mxdibuilder.com | (628) 304 6934 | GC, remodel, ADU | Hercules · Contra Costa County | — | — |
| My Generator Guy And Powerhouse Construction | Gregory Steven Cocotis | — | (925) 432 6291 | Electricians | Pittsburg · Contra Costa County | — | — |
| Myers Painting | Myers Painting | — | (925) 813 8067 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Myfort Corp | Babatunde Olumide Adefolaju | — | (925) 922 0594 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Myriad Builders INC | Elijah Jack Wilks | — | (510) 502 6494 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Mz2 Builder | Mz2 Builder | — | (510) 230 9844 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| N A B Construction INC | Nate Biron | — | (925) 818 0185 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| N Abeyta Remodels | N Abeyta Remodels | — | (925) 584 0818 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| N E Construction | Jose Nicasio Escamilla Chan | estimating@neconstruction.com | (415) 377 1387 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| N I C Construction | William Edward Nicholls | — | (925) 382 7549 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| N K Heating & Air Conditioning INC | Nelson David Kigenyi | — | (925) 682 0482 | HVAC | Antioch · Contra Costa County | — | — |
| N P Rooter & Plumbing | N P Rooter & Plumbing | — | (415) 299 4277 | Other | San Pablo · Contra Costa County | — | — |
| N R L Electric | Nicholas Richard Luoma | — | (925) 813 2255 | Electricians | Discovery Bay · Contra Costa County | — | — |
| N S General Contractors INC | Stavrianopoulos Antone | — | (925) 915 5686 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| N V Construction | Vargas Nicolas | — | (925) 384 8423 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| N V Heathorn Co | David Clayton Wenner | — | (510) 569 9100 | Other roofers | Concord · Contra Costa County | — | — |
| N-p-m Landscape | Bernardo Macias | — | (510) 526 9698 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Nahas Company | Randall Evan Nahas | — | (510) 719 0266 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| Nails & Wood Builder's INC | Jaime David Vega Beltran | — | (510) 978 3902 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Nairi's Home Improvement Services | Nairi Yurik Muradyan | — | (925) 978 7871 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Nak For Plumbing INC | Keiko Hashimoto Nakagaki | service@nakforplumbing.com | (925) 969 0194 | Other | Martinez · Contra Costa County | — | — |
| Nakahama Construction | Nakahama Ichiro | — | (510) 329 0829 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |