| A I G Painting | A I G Painting | — | (530) 979 0550 | GC, remodel, ADU | Arbuckle · Colusa County | — | — |
| A. Nichols Tree Service And Excavating | A. Nichols Tree Service And Excavating | — | (707) 272-3362 | Tree | Cobb · Colusa County | — | — |
| Abs Builders INC | Amy Marie Gwinnup | — | (530) 458 2299 | GC, remodel, ADU | Colusa · Colusa County | — | — |
| Acero Ca Building Components | Acero Ca Building Components | — | (530) 458-5800 | Windows, patio, painters | Colusa · Colusa County | — | — |
| Aceves Tree Care INC | Ricardo Humberto Jr Aceves | — | (530) 812 3432 | Tree | Williams · Colusa County | — | — |
| Advance Services Inc. | Advance Services Inc. | — | (530) 379-0230 | Alarm and generators | Colusa · Colusa County | — | — |
| Aks Construction | Aks Construction | — | (530) 458-8700 | Pool | Colusa · Colusa County | — | — |
| Alsco - Geyer Irrigation INC | Andy Charles Geyer | — | (530) 476 2253 | Other | Arbuckle · Colusa County | — | — |
| Alton Air Duct Service | Alton Air Duct Service | — | (866) 798-9150 | HVAC | Colusa · Colusa County | — | — |
| American Carports INC | American Carports INC | — | (530) 763-0051 | GC, remodel, ADU | Colusa · Colusa County | — | — |
| Apxg Heating And Air Conditioning | Apxg Heating And Air Conditioning | — | (530) 491 8885 | HVAC | Williams · Colusa County | — | — |
| Arrow S Company INC | Lori Michelle Skaggs | — | (707) 396 0073 | Other | Arbuckle · Colusa County | — | — |
| Asa Charles Smith | Asa Charles Smith | — | (530) 330 1900 | Other | Williams · Colusa County | — | — |
| Baker Systems Inc. | Baker Systems Inc. | info@bakersystems.net | (800) 986-2372 | Alarm and generators | Upland · Colusa County | — | — |
| Barmann Landscape & Irrigation | Barmann Landscape & Irrigation | — | (530) 870 2473 | Windows, patio, painters | Colusa · Colusa County | — | — |
| Brothers Roofing Company | Brothers Roofing Company | — | (760) 550-6158 | Other roofers | Brawley · Colusa County | — | — |
| Brush Masters Painting INC | Brush Masters Painting INC | info@brushmasterspainting-inc.com | (209) 937-3603 | Windows, patio, painters | Lathrop · Colusa County | — | — |
| Burgess And Sons Excavating INC | David Marlin Burgess | — | (530) 848 1253 | Other | Arbuckle · Colusa County | — | — |
| Buttars Yard Service INC | Tracy Scott Buttars | — | (530) 501 8289 | Windows, patio, painters | Arbuckle · Colusa County | — | — |
| C & L Electric | Guzman Leonardo | — | (530) 458 1919 | Electricians | Colusa · Colusa County | — | — |
| C P S | C P S | — | (530) 682 2378 | Other | Princeton · Colusa County | — | — |
| C2 Electric INC | Fabian Valles | — | (530) 379 6491 | Electricians | Arbuckle · Colusa County | — | — |
| Calfab Steel | Calfab Steel | — | (530) 570 3629 | Other | Colusa · Colusa County | — | — |
| California Security Pro | California Security Pro | — | (800) 310-9490 | Alarm and generators | Colusa · Colusa County | — | — |
| Campiz Electric | Ernesto G Campiz | — | (530) 383 3389 | Electricians | Arbuckle · Colusa County | — | — |
| Cano Legacy Roofing INC | Jose Guadalupe Cano Velazquez | — | (530) 635 0651 | Other roofers | Arbuckle · Colusa County | — | — |
| Carvalho's Heating And Air Conditioning INC | David Manuel Jr Carvalho | — | (530) 438 2999 | HVAC | Maxwell · Colusa County | — | — |
| Charles C Geyer DBA Alsco Geyer Irrigation | Alsco Geyer Irrigation | — | (530) 476 2253 | Other | Arbuckle · Colusa County | — | — |
| Charles M Fusaro Construction | Donna Lynn Fusaro | — | (530) 635 3625 | GC, remodel, ADU | Colusa · Colusa County | — | — |
| Charlies Electric INC | Charles Joseph Meyers | — | (530) 682 5822 | Electricians | Colusa · Colusa County | — | — |
| Charter Heating & Air Conditioning | Charter Heating & Air Conditioning | — | (530) 682 5176 | HVAC | Arbuckle · Colusa County | — | — |
| Clear Line Plumbing | Clear Line Plumbing | — | (530) 966 4577 | Other | Arbuckle · Colusa County | — | — |
| Clearcast Concrete & Stone Products | Clearcast Concrete & Stone Products | — | (530) 458-1115 | GC, remodel, ADU | Colusa · Colusa County | — | — |
| Climate Duct Solutions | Climate Duct Solutions | — | (530) 551-0462 | GC, remodel, ADU | Colusa · Colusa County | — | — |
| Colusa Building Inspector | Colusa Building Inspector | buildinginspections@cityofcolusa.com | (530) 458-4740 | Inspectors | Colusa · Colusa County | — | — |
| Colusa County Animal Control | Colusa County Animal Control | — | (530) 458-0168 | Pest, tile roofs | Colusa · Colusa County | — | — |
| Colusa County Arts Council | Colusa County Arts Council | — | (530) 458-2222 | Windows, patio, painters | Colusa · Colusa County | — | — |
| Colusa County Fairgrounds | Colusa County Fairgrounds | — | (530) 458-2641 | Alarm and generators | Colusa · Colusa County | — | — |
| Colusa County Glass | Colusa County Glass | — | (530) 458 5797 | Windows, patio, painters | Colusa · Colusa County | — | — |
| Colusa Garden | Colusa Garden | — | (530) 458-7811 | Alarm and generators | Colusa · Colusa County | — | — |