| Milne Mechanical Corporation | Justin Eddie Milne | — | (707) 812 3738 | HVAC | Middletown · Lake County | — | — |
| Mission Viejo Heating & Air | Mission Viejo Heating & Air | — | (949) 540-8142 | HVAC | Lake Forest · Lake County | — | — |
| Modern Painting & Decorating | Modern Painting & Decorating | — | (707) 350 1676 | Windows, patio, painters | Clearlake · Lake County | — | — |
| Monhoff Builders | Monhoff Builders | — | (707) 479 8683 | GC, remodel, ADU | Middletown · Lake County | — | — |
| Monte's Fireplace Service | Sean Wane Christmann | — | (707) 624 5608 | Other | Kelseyville · Lake County | — | — |
| Morris Painting | Morris Painting | — | (707) 479 3374 | Windows, patio, painters | Hidden Valley Lake · Lake County | — | — |
| Morrison's Heavenly Floors | Morrison's Heavenly Floors | — | (707) 295 5067 | Other | Clearlake · Lake County | — | — |
| Mount St Helena Plumbing | Mount St Helena Plumbing | — | (707) 987 9804 | Other | Middletown · Lake County | — | — |
| Mulka Construction | Joshua Elmo Mulka | — | (707) 349 2988 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Napa Auto Parts - Lake Elsinore | Napa Auto Parts - Lake Elsinore | — | (951) 674-9048 | Windows, patio, painters | Lake Elsinore · Lake County | — | — |
| Nate's Electric INC | Nathan Michael Guistolise | — | (707) 278 0176 | Electricians | Kelseyville · Lake County | — | — |
| Nathan Johnson Painting | Nathan Johnson Painting | — | (707) 892 1167 | Windows, patio, painters | Cobb · Lake County | — | — |
| Nazarene Painting LLC | Eli Kenneth Andrews | — | (707) 295 0866 | Windows, patio, painters | Clearlake · Lake County | — | — |
| Next Level Construction And Restoration INC | Timothy Michael Wilson | — | (707) 477 6963 | GC, remodel, ADU | Lower Lake · Lake County | — | — |
| Noah Torkelsen | Noah Torkelsen | — | (707) 227 7755 | Other | Middletown · Lake County | — | — |
| Nor - Cal Tree Service | Don Thomas Lasbury | — | (707) 621 0885 | Tree | Kelseyville · Lake County | — | — |
| Nor-cal Telecom | Nor-cal Telecom | — | (707) 279 2070 | Other | Kelseyville · Lake County | — | — |
| North Coast Plastering | Jason Allen White | — | (707) 295 8055 | GC, remodel, ADU | Hidden Valley Lake · Lake County | — | — |
| North Counties Development Corporation | Berndt Olaf Akerstrom | — | (707) 462 7166 | Other | Lakeport · Lake County | — | — |
| North Lake Electrical | North Lake Electrical | service@northlakeelectrical.com | (949) 543-0913 | Electricians | Irvine · Lake County | — | — |
| Northwestern Independent Construction | Devon Eugene Vr Meer | — | (707) 849 2193 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Novelty Home | Novelty Home | — | (707) 235 9576 | GC, remodel, ADU | Cobb · Lake County | — | — |
| O & Jj's LLC | Ibarra Juvenal Campos | — | (707) 295 8008 | GC, remodel, ADU | Middletown · Lake County | — | — |
| O'connor Landscaping Management | O'connor Landscaping Management | — | (951) 897 7596 | Windows, patio, painters | Clearlake Oaks · Lake County | — | — |
| Oakline Tree Experts | Oakline Tree Experts | — | (707) 245 1413 | Other | Glenhaven · Lake County | — | — |
| Oakside Builders LLC | Sergio Jr Ornelas | — | (707) 217 3081 | GC, remodel, ADU | Hidden Valley Lake · Lake County | — | — |
| Obm Construction INC | Zuniga Sergio Olivares | — | (707) 548 6124 | GC, remodel, ADU | Clearlake · Lake County | — | — |
| Odom Construction | Matthew William Odom | — | (707) 263 1359 | GC, remodel, ADU | Lakeport · Lake County | — | — |
| Olea Landscaping Services | Olea Vargas Diego | — | (707) 391 2197 | Windows, patio, painters | Lakeport · Lake County | — | — |
| Orbital Management | Orbital Management | — | (707) 478 3263 | GC, remodel, ADU | Cobb · Lake County | — | — |
| P C Electric | Patrice Alexandra Conklin | office@pcelectric.at | (707) 339 0686 | Electricians | Middletown · Lake County | — | — |
| Pabst Blue Ribbon General Construction INC | Dustin Brian Pabst | — | (707) 349 1710 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Pacific Integrated Access LLC | Gregory Orin Alford | — | (707) 467 7130 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Pacific Marine Construction | Pacific Marine Construction | — | (951) 678-5872 | GC, remodel, ADU | Lake Elsinore · Lake County | — | — |
| Pagan Painting | Adrian Lloyd Pagan | — | (707) 490 5398 | Windows, patio, painters | Kelseyville · Lake County | — | — |
| Parker Construction Company | Daniel Edward Parker | — | (707) 249 1640 | GC, remodel, ADU | Middletown · Lake County | — | — |
| Patio Covers And More INC | Dennis Dominic Klein | — | (707) 850 9574 | GC, remodel, ADU | Hidden Valley Lake · Lake County | — | — |
| Paulette M Allen DBA D & P Pools | D & P Pools | — | (707) 263 3464 | GC, remodel, ADU | Middletown · Lake County | — | — |
| Peninsula Construction | William Thomas Papa | — | (650) 743 5446 | GC, remodel, ADU | Middletown · Lake County | — | — |
| People Services INC | Dana Galyn Lewis | — | (707) 263 3810 | Windows, patio, painters | Lakeport · Lake County | — | — |