| Monrad Builders | Monrad Builders | — | (707) 499 9770 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Moody's Construction | Jeffrey Raymond Moody | — | (707) 223 0203 | GC, remodel, ADU | Garberville · Humboldt County | — | — |
| Moonstone Construction | Paul Reid Hasselquist | — | (707) 599 5164 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| Moore Construction Co | Thomas Vernon Moore | — | (707) 502 0731 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| Moore's Roofing And Services | Todd Owen Moore | — | (707) 444 3432 | Other roofers | Eureka · Humboldt County | — | — |
| Morais Steven Excavating | Morais Steven Excavating | — | (707) 599 6962 | Other | Mc Kinleyville · Humboldt County | — | — |
| Moreno's Painting | Moreno's Painting | — | (707) 498 1577 | Windows, patio, painters | Eureka · Humboldt County | — | — |
| Mortimer Plumbing Construction INC | Timothy John Mortimer | — | (707) 839 9111 | Other | Mc Kinleyville · Humboldt County | — | — |
| Moxon Construction | Galen David Moxon | — | (707) 496 4414 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Mp Construction | Malachi Ross Pratton | — | (707) 672 3229 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Mr Matt's Mudworks | Mr Matt's Mudworks | — | (707) 362 7664 | Other | Mc Kinleyville · Humboldt County | — | — |
| Mr Rooter Plumbing | Mr Rooter Plumbing | — | (707) 443 9222 | Other | Eureka · Humboldt County | — | — |
| Mrb Construction | Michael Robert Bray | mrbconstruction1995@gmail.com | (306) 460-8700 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Muddy Boots Landscaping | Muddy Boots Landscaping | — | (707) 845 7479 | Windows, patio, painters | Blue Lake · Humboldt County | — | — |
| Mueting Engineering | Mueting Engineering | — | (559) 280 8114 | Other | Bayside · Humboldt County | — | — |
| Mulder Construction Company | Thomas Theodore Mulder | — | (707) 601 0260 | Other | Garberville · Humboldt County | — | — |
| Munoz Osorio Construction | Munoz Osorio Misahell | — | (707) 845 9284 | GC, remodel, ADU | Carlotta · Humboldt County | — | — |
| Muro Electric | Muro Rufino | muroelectric@gmail.com | (707) 407 7527 | Electricians | Fortuna · Humboldt County | — | — |
| Murray Plumbing | Murray Plumbing | service@murrayplumbing.com | (707) 496 5315 | Other | Hydesville · Humboldt County | — | — |
| Myckle Solotoff Construction | Myckle David Solotoff | — | (707) 498 8233 | GC, remodel, ADU | Carlotta · Humboldt County | — | — |
| Myles Clark Construction | Myles Sterling Clark | — | (707) 498 9923 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Nathan Pelosa Painting | Nathan Pelosa Painting | — | (707) 498 5857 | Windows, patio, painters | Loleta · Humboldt County | — | — |
| Native Ecosystems | Hugh John Mcgee | — | (707) 599 7814 | Windows, patio, painters | Arcata · Humboldt County | — | — |
| Native Seamless Gutters | Native Seamless Gutters | — | (707) 499 7377 | Other | Hoopa · Humboldt County | — | — |
| Natuwall | Steven Simoes Regalo | — | (707) 498 5823 | Other | Trinidad · Humboldt County | — | — |
| Neal J Mc Kenny Corporation | Neal Joseph Mc Kenny | — | (707) 498 7671 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| Ned Harwood Construction | Edward Patterson Harwood | — | (707) 223 0216 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| Neil's Specialty Sound | Neil's Specialty Sound | — | (707) 407-0157 | Alarm and generators | Eureka · Humboldt County | — | — |
| Nelson Floors | Timothy Andrew Vernig | — | (707) 442 2987 | Other | Eureka · Humboldt County | — | — |
| New Creations Home Improvement | New Creations Home Improvement | — | (707) 496 0518 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| New Dimensions Construction | Sunshine William Simmons | — | (707) 496 5550 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| New Horizon Drywall Construction INC | Gerald Andrew Mc Gillivray | — | (707) 725 9113 | Other | Fortuna · Humboldt County | — | — |
| New Life Vinyl INC DBA New Life Service Co | William Steven Crassweller | — | (707) 444 8222 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Newby Construction | Glenn L Newby | — | (707) 499 7194 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Nick And Sharon Mitchell | Nicholas Colon Mitchell | — | (707) 599 2353 | Other | Bayside · Humboldt County | — | — |
| Nickerson Construction | Scott Alan Nickerson | — | (707) 496 2191 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Niekrasz Plumbing INC | Gregory Albert Niekrasz | — | (707) 442 7181 | HVAC | Eureka · Humboldt County | — | — |
| Nor Cal Mechanical LLC | Janice Mary Masterson | shawn@norcalmechanical.com | (707) 223 2100 | HVAC | Garberville · Humboldt County | — | — |
| Nor-cal Construction | Randall Paul Mcgaughey | — | (707) 298 0918 | Other | Mc Kinleyville · Humboldt County | — | — |
| Norcal Exterior | Byron Jon Stocum | info@norcalexterior.com | (707) 798 7066 | GC, remodel, ADU | Samoa · Humboldt County | — | — |