| 101 Plumbing Humboldt INC | Isaac Arizona Kennedy | — | (707) 498 2707 | Other | Eureka · Humboldt County | — | — |
| 6 Rivers Construction INC | Zane Eldon Jr Grant | arielle.pennington@riversconstruction.com | (530) 515 7563 | Other | Hoopa · Humboldt County | — | — |
| 6 Rivers Electric | Peter Raymond Dauphinee | — | (707) 616 4781 | Electricians | Blue Lake · Humboldt County | — | — |
| 707 Builders | 707 Builders | — | (707) 601 3825 | GC, remodel, ADU | Bayside · Humboldt County | — | — |
| A & A Painting | A & A Painting | interested@domainmarket.com | (707) 845 3643 | Windows, patio, painters | Eureka · Humboldt County | — | — |
| A & B Roofing | Andrew Jackson Evans | — | (707) 296 8179 | Other roofers | Fortuna · Humboldt County | — | — |
| A & I Roofing INC | Julia Ann Christian | cschario@gmail.com | (707) 826 2653 | Other roofers | Arcata · Humboldt County | — | — |
| A & M Builders LLC | Alan George Parks | — | (707) 834 1315 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| A And G Concrete | Steve Dennis Ambrosini | — | (707) 832 6079 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| A Bean Electric | Alexander Boston Bean | — | (707) 498 4036 | Electricians | Eureka · Humboldt County | — | — |
| A F Contracting | James Allen Alves | — | (707) 601 1008 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| A Lefevre General Contractor | A Lefevre General Contractor | — | (707) 845 6317 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| A T C | A T C | — | (707) 499 2618 | Electricians | Mc Kinleyville · Humboldt County | — | — |
| A W Painting | A W Painting | scheduleawpainting@gmail.com | (707) 497 7858 | Windows, patio, painters | Mc Kinleyville · Humboldt County | — | — |
| Aaron Dulitz | Aaron Dulitz | — | (805) 459 3928 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| Aaron Thomas Construction | Aaron Matthew Thomas | — | (707) 298 7369 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Aaron's Construction | Aaron Rollan Moschetti | — | (707) 496 0180 | GC, remodel, ADU | Scotia · Humboldt County | — | — |
| Abbott Plumbing | Abbott Plumbing | — | (707) 499 5186 | Other | Arcata · Humboldt County | — | — |
| Abco-american Building Company | Gregory William Schneider | — | (707) 677 3714 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| Abercrombie Construction | Jeffrey Michael Abercrombie | — | (707) 845 1794 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Abundance Builders | Wesley Hamilton Hodges | — | (707) 834 1870 | Electricians | Mc Kinleyville · Humboldt County | — | — |
| Adams Commercial General Contracting INC | Will Edward Adams | — | (707) 443 6000 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Adams Construction | Stephen Larry Allen Adams | — | (707) 496 0557 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| Advanced Painting And Decorating | Courtney Martin Hall | — | (707) 499 1288 | Windows, patio, painters | Blue Lake · Humboldt County | — | — |
| Advanced Security Systems | Michael Richard Petrusha | interested@domainmarket.com | (707) 443 6366 | Electricians | Eureka · Humboldt County | — | — |
| Agland Engineering INC | Steven Robert Hackett | — | (707) 786 4044 | Other | Ferndale · Humboldt County | — | — |
| Agliolo's Quality Painting & Restoration | Agliolo's Quality Painting & Restoration | — | (707) 845 3192 | Windows, patio, painters | Mc Kinleyville · Humboldt County | — | — |
| Air Tight | Jackie Lou Mc Beth | — | (707) 822 8800 | HVAC | Arcata · Humboldt County | — | — |
| Alan Bongio Construction INC | Alan Paul Bongio | — | (707) 499 5820 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Alba Plumbing And Fire Protection INC | Joshua Ryan Conley | — | (707) 834 1213 | Other | Eureka · Humboldt County | — | — |
| Albers Construction | Michael Shane Albers | keith@albersdc.com | (707) 764 2204 | Other | Rio Dell · Humboldt County | — | — |
| Alchemy Construction Incorporated | Amy Christine Bohner | — | (707) 822 8013 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| All Construction And Electric | Ethan Samuel Jacobs | — | (707) 496 4309 | Electricians | Mc Kinleyville · Humboldt County | — | — |
| Allen Epperly Construction | Allen Hopkins Epperly | — | (707) 599 7723 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| Allen Painting | Allen Painting | — | (707) 496 0114 | Windows, patio, painters | Fortuna · Humboldt County | — | — |
| Allpoints Advertising INC | Geoffrey Howard Wills | — | (714) 655 0763 | Other | Eureka · Humboldt County | — | — |
| Alternative Building Services | Michael James Matson | — | (707) 616 4131 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| Alves INC | Jeffrey Lee Alves | — | (707) 825 4725 | Other roofers | Arcata · Humboldt County | — | — |
| Ameri-construction | David Kyle Koltko | — | (707) 498 7873 | GC, remodel, ADU | Ferndale · Humboldt County | — | — |
| American Electric | David Jon Winters | — | (707) 498 3513 | Electricians | Redway · Humboldt County | — | — |