| Bungalow Construction | Derek Gene Glavich | — | (707) 267 5597 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Burgess Electric | Douglas Anthony Burgess | — | (707) 496 2862 | Electricians | Fortuna · Humboldt County | — | — |
| Bushnell Well Drilling | Bushnell Well Drilling | — | (707) 943 3617 | Other | Miranda · Humboldt County | — | — |
| C C S Construction | Cory Calvin Sehon | — | (707) 498 0568 | GC, remodel, ADU | Cutten · Humboldt County | — | — |
| C M Construction | Fonseca Manuel | — | (707) 845 6969 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| C N Mc Gahan | C N Mc Gahan | — | (707) 326 9788 | GC, remodel, ADU | Fields Landing · Humboldt County | — | — |
| C R Fence Company INC DBA Humboldt Fence Company | Russell Steven Renner | — | (707) 726 7965 | Other | Fortuna · Humboldt County | — | — |
| C. Donnelly Builds | C. Donnelly Builds | — | (707) 834 4479 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| Ca Construction | Charleton Allen Russell | — | (707) 223 8503 | GC, remodel, ADU | Whitethorn · Humboldt County | — | — |
| Cabinets By Andy | Andrew Bryan Dickey | — | (707) 839 0220 | Other | Mc Kinleyville · Humboldt County | — | — |
| Cacren Fencing | Cacren Fencing | — | (707) 496 3870 | Other | Rio Dell · Humboldt County | — | — |
| Cafferata Construction INC | Michael Robert Cafferata | — | (707) 267 0114 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Cal Eco Pest | Cal Eco Pest | caleco.humboldt@aol.com | (707) 601-4191 | Pest, tile roofs | Fortuna · Humboldt County | — | — |
| Cal Fisher Construction | Calvin Bryant Fisher | — | (707) 499 5704 | GC, remodel, ADU | Rio Dell · Humboldt County | — | — |
| Cal Plumbing & Fire Suppression INC | Ryan Frank Rousseau | — | (707) 499 2631 | Other | Blue Lake · Humboldt County | — | — |
| Caledonia Plumbing | Caledonia Plumbing | — | (707) 845 1242 | Other | Carlotta · Humboldt County | — | — |
| California Construction Company | Paul Walter Schneekluth | — | (707) 442 8987 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| California Edge Painting LLC | Gabriel Jesus Saille | info@californiaedgepainting.com | (707) 362 2737 | Windows, patio, painters | Mc Kinleyville · Humboldt County | — | — |
| Canyon Sam Treman | Canyon Sam Treman | — | (707) 834 1501 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Capital Electric INC | Ransom Kyle Reid | — | (949) 599 4287 | Electricians | Whitethorn · Humboldt County | — | — |
| Carbonneau Ceramic Tile Incorporated | Pierre Gerald Carbonneau | — | (707) 443 8842 | Other | Eureka · Humboldt County | — | — |
| Carl Zapf | Carl Zapf | — | (707) 445 8366 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Carlin Construction | Kelly Trevor Carlin | — | (707) 267 8153 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| Carpe Diem Construction | Jeffrey Scott Hesseltine | — | (707) 498 5217 | GC, remodel, ADU | Trinidad · Humboldt County | — | — |
| Carpet Depot | Daniel Eugene Mealhouse | — | (707) 442 3470 | Other | Eureka · Humboldt County | — | — |
| Carson Frint Construction | Carson Charles Frint | — | (707) 834 1404 | GC, remodel, ADU | Arcata · Humboldt County | — | — |
| Cbl Construction | Casey Brenton Lund | — | (707) 496 0125 | GC, remodel, ADU | Ferndale · Humboldt County | — | — |
| Cdh Painting INC | Clayton Duane Hagans | — | (707) 443 4429 | Windows, patio, painters | Eureka · Humboldt County | — | — |
| Cedar Bay Plumbing | Cedar Bay Plumbing | — | (707) 499 6119 | Other | Eureka · Humboldt County | — | — |
| Century Mobile Homes | Century Mobile Homes | — | (707) 445 8411 | Other | Eureka · Humboldt County | — | — |
| Chad Sefton Construction | Chad David Sefton | — | (707) 834 6980 | GC, remodel, ADU | Hydesville · Humboldt County | — | — |
| Chamberlain Chimney Sweep | Chamberlain Chimney Sweep | — | (707) 443 5906 | Other | Eureka · Humboldt County | — | — |
| Charles Mondragon Construction | Mondragon Charles Cosntruction | — | (707) 834 9978 | GC, remodel, ADU | Mc Kinleyville · Humboldt County | — | — |
| Charles Nganga Flooring | Charles Nganga Flooring | — | (707) 407 5863 | Other | Eureka · Humboldt County | — | — |
| Charles Rockwood | Charles Rockwood | — | (707) 273 8431 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Charleston Tree Services | Graham Andrew Charleston | — | (707) 497 4471 | Tree | Mc Kinleyville · Humboldt County | — | — |
| Chm Construction | Cesar Hazael Moreno | chm.construction01@gmail.com | (707) 267 7573 | GC, remodel, ADU | Cutten · Humboldt County | — | — |
| Chris Clayton Construction Co | Christopher Douglas Clayton | — | (707) 599 8822 | GC, remodel, ADU | Eureka · Humboldt County | — | — |
| Chris Custom Carpentry | Chris Custom Carpentry | — | (707) 498 2804 | GC, remodel, ADU | Fortuna · Humboldt County | — | — |
| Chris Hatton Construction INC | Christopher Robert Hatton | — | (530) 448 6586 | GC, remodel, ADU | Whitethorn · Humboldt County | — | — |