| Nissim Painting INC | Jack Albert Nissim | admin@nissimpainting.com | (415) 566 5111 | Windows, patio, painters | Napa · Napa County | — | — |
| Nivco Construction Corporation | Michael Yervant Nivens | — | (707) 224 4141 | GC, remodel, ADU | Napa · Napa County | — | — |
| Noble House Construction & Development INC | Steven Gary Hasty | — | (707) 257 3482 | GC, remodel, ADU | Napa · Napa County | — | — |
| Norgo Engineering | Gonzalez Juan Noriega | — | (510) 932 5712 | Other | American Canyon · Napa County | — | — |
| Norris Electrical Services | Peter Joshua Norris | — | (707) 569 4847 | Electricians | Calistoga · Napa County | — | — |
| North Bay Courts | David Douglas Jefferson | — | (707) 255 1555 | Other | Napa · Napa County | — | — |
| North Bay General Builder | North Bay General Builder | — | (707) 333 1811 | GC, remodel, ADU | Napa · Napa County | — | — |
| North Bay Painting Services INC | James Phillip Di Rienzo | — | (705) 482-1142 | Windows, patio, painters | Napa · Napa County | — | — |
| North Bay Tile Co | Michael Jerry Eoff | — | (707) 257 0405 | Other | St Helena · Napa County | — | — |
| North Bay Water Heater Solutions | Jeremiah Albert Botts | — | (707) 968 1369 | Other | Napa · Napa County | — | — |
| North Valley Glass | North Valley Glass | — | (707) 974 6991 | Windows, patio, painters | Napa · Napa County | — | — |
| Northbay Landscaping And Design LLC | Montesinos Alexis Bautista | — | (707) 681 4800 | Windows, patio, painters | Calistoga · Napa County | — | — |
| Northwood Landscaping LLC | Alcala Angel | micah@micahrich.com | (707) 812 9014 | Windows, patio, painters | Napa · Napa County | — | — |
| Nortrek Solutions | Nortrek Solutions | — | (707) 656 5656 | GC, remodel, ADU | Napa · Napa County | — | — |
| Nova Designs Builds INC | John Edward Schrader | — | (415) 730 3416 | GC, remodel, ADU | Napa · Napa County | — | — |
| Nova Group INC | Drew Alexander Glover | — | (707) 265 1100 | Electricians | Napa · Napa County | — | — |
| Nova Probst A Joint Venture | Group INC Nova | — | (707) 265 1100 | Electricians | Napa · Napa County | — | — |
| Np Landscaping Services | Sanh Pham | — | (707) 653 2988 | Windows, patio, painters | American Canyon · Napa County | — | — |
| Nws General Construction | Nicholas William Jr Sanza | — | (707) 815 8359 | GC, remodel, ADU | Napa · Napa County | — | — |
| O G Plumbing | O G Plumbing | — | (707) 694 5155 | Other | Napa · Napa County | — | — |
| O'brien Builders | Jack Clancy O'brien | info@obrienbuilders.com | (707) 864 2615 | GC, remodel, ADU | Napa · Napa County | — | — |
| Oak Design And Build | Samuel David Von Fange | hello@oakdesignbuild.com | (707) 681 5858 | GC, remodel, ADU | Napa · Napa County | — | — |
| Oak Knoll Electric | Timothy John Conatser | — | (707) 337 0556 | Electricians | Napa · Napa County | — | — |
| Oakville Pump Service INC | Nicholaus Ernest Lutz | — | (707) 944 2471 | Electricians | Napa · Napa County | — | — |
| Obra Napa Design Build | Torres Javier Sanchez | — | (707) 294 0975 | GC, remodel, ADU | Napa · Napa County | — | — |
| Oden & Doucette INC | George Edward Schenecker | — | (707) 255 2207 | Windows, patio, painters | Napa · Napa County | — | — |
| Ogletree's INC | Matthew Silvio Cia | — | (707) 963 3537 | Other | St Helena · Napa County | — | — |
| Olde World Designs | Olde World Designs | — | (707) 944 8548 | GC, remodel, ADU | Oakville · Napa County | — | — |
| Oldenbrook Design/build | Oldenbrook Design/build | — | (415) 867 9595 | GC, remodel, ADU | Napa · Napa County | — | — |
| Omni La Costa Resort & Spa | Omni La Costa Resort & Spa | — | (760) 438-9111 | Pool | Carlsbad · Napa County | — | — |
| Organ Drywall | Organ Drywall | — | (707) 287 1826 | Other | Napa · Napa County | — | — |
| Oscar Tree Services INC | Oscar Fernando Perez | — | (650) 787 2006 | Tree | Napa · Napa County | — | — |
| Oscar's Tree Service | Oscar's Tree Service | oscartreebayarea22@gmail.com | (707) 260-4420 | Tree | Napa · Napa County | — | — |
| Oxbow Pool & Landscape Contractors | Charles Peter Haeuser | — | (707) 501 7038 | Windows, patio, painters | Napa · Napa County | — | — |
| Oxbow Pool And Landscape Contractors | Oxbow Pool And Landscape Contractors | — | (707) 339-6001 | Pool | Napa · Napa County | — | — |
| P & R Septic Systems LLC | Mark Joseph Phillips | — | (707) 252 6866 | Other | Napa · Napa County | — | — |
| P M H Construction | Patrick Michael Hodge | — | (707) 333 6647 | GC, remodel, ADU | Napa · Napa County | — | — |
| P S Woodworking | P S Woodworking | — | (707) 251 9255 | Other | Napa · Napa County | — | — |
| Pacific Electric | Garrett Wayne Hale | — | (707) 255 5836 | Electricians | Napa · Napa County | — | — |
| Paco's Painting | Paco's Painting | — | (707) 320 3954 | Windows, patio, painters | Pope Valley · Napa County | — | — |