| Coast Tile Company | Eric Miles Cissna | — | (707) 291 3227 | Other | Gualala · Mendocino County | — | — |
| Coastal Current Electric LLC | Caleb Daniel Mileham | estimates@coastalcurrentelectric.com | (949) 801-6009 | Electricians | Point Arena · Mendocino County | — | — |
| Coastal Painting | Coastal Painting | — | (707) 962 7266 | Windows, patio, painters | Littleriver · Mendocino County | — | — |
| Coastal Renovations | Coastal Renovations | interested@domainmarket.com | (707) 684 6502 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Coastal Well Cleaning | Coastal Well Cleaning | — | (707) 964 5939 | Other | Fort Bragg · Mendocino County | — | — |
| Coleman Plumbing | Coleman Plumbing | — | (707) 485 2854 | Other | Redwood Valley · Mendocino County | — | — |
| Collicott Construction | Nathaniel Edward Collicott | — | (707) 489 5928 | GC, remodel, ADU | Willits · Mendocino County | — | — |
| Comfort Air Of Ukiah | Fernando Cortez Arcila | doug@homepro-hvac.com | (707) 462 4328 | HVAC | Ukiah · Mendocino County | — | — |
| Concrete Pete INC | Peter Raymond Jr| Gallegos Pete Raymond Gallegos | pete@concretepete.com | (707) 472 6918 | Other | Ukiah · Mendocino County | — | — |
| Connected Electric | Kyle David Harney | — | (415) 419 5974 | Electricians | Fort Bragg · Mendocino County | — | — |
| Contreras Construction | Antonio Arturo Contreras | bids@contrerasconstructioncorp.com | (707) 380 7310 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Contreras Roofing | Salvador Puentes Contreras | — | (707) 795 9595 | Other roofers | Ukiah · Mendocino County | — | — |
| Cooley Ryan N | Cooley Ryan N | — | (707) 489 6628 | GC, remodel, ADU | Talmage · Mendocino County | — | — |
| Cooper Plumbing | Cooper Plumbing | — | (707) 962 3017 | Other | Fort Bragg · Mendocino County | — | — |
| Cooper Plumbing INC | Micah John Cooper | — | (707) 962 3017 | Other | Fort Bragg · Mendocino County | — | — |
| Cora Saxton | Cora Saxton | — | (707) 621 1960 | Electricians | Willits · Mendocino County | — | — |
| Corestone | Sean Beau Devito | itsyournames@gmail.com | (707) 223 7919 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Corner Bit Excavation | Sheldon Guy Smith | info@cornerbitexcavation.com | (707) 354 0120 | Tree | Willits · Mendocino County | — | — |
| Cornerstone Construction | Michael Benjamin Simila | gwebb@cornerstone-construction.com | (832) 259-2520 | GC, remodel, ADU | Gualala · Mendocino County | — | — |
| Countryside Creations INC | Mark Allen Anderson | — | (707) 357 4150 | GC, remodel, ADU | Comptche · Mendocino County | — | — |
| Covenant Building And Remodeling | Covenant Building And Remodeling | — | (857) 247 6779 | GC, remodel, ADU | Fort Bragg · Mendocino County | — | — |
| Craft Electric Services INC | Glenn Robbin Floyd | — | (707) 486 9610 | Electricians | Willits · Mendocino County | — | — |
| Craig Titus | Craig Titus | — | (707) 895 3424 | Other | Boonville · Mendocino County | — | — |
| Crane Of Ukiah | Francine Crane Selim | — | (707) 462-1412 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Cranium Construction | Nathan Joseph Hake | — | (707) 478 7209 | GC, remodel, ADU | Point Arena · Mendocino County | — | — |
| Crazy Viking Building Services | Ceven C Christiansen | — | (707) 391 5776 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Creative Landscaping | Creative Landscaping | — | (707) 462 0435 | Windows, patio, painters | Ukiah · Mendocino County | — | — |
| Creekside Landscaping | Creekside Landscaping | — | (707) 318 4480 | Windows, patio, painters | Hopland · Mendocino County | — | — |
| Cronin's Custom Metals | Cronin's Custom Metals | — | (707) 813 4593 | Other | Fort Bragg · Mendocino County | — | — |
| Crosetti Excavation INC | Lee Orin Howard | — | (707) 989 8974 | Other | Ukiah · Mendocino County | — | — |
| Cross Country Property Development And Excavation | Danny Robert Pardini | — | (707) 272 5916 | Other | Boonville · Mendocino County | — | — |
| Crudo Construction | Mike Patrick Crudo | — | (707) 489 0127 | GC, remodel, ADU | Ukiah · Mendocino County | — | — |
| Cupples & Sons Construction INC | Rickey Lynn Cupples | — | (707) 972 5277 | GC, remodel, ADU | Hopland · Mendocino County | — | — |
| Cupples & Sons Construction/cupples Excavating | & Sons Construction INC Cupples | — | (707) 972 5277 | GC, remodel, ADU | Hopland · Mendocino County | — | — |
| Cupples Excavating INC | Cole Matthew Cupples | — | (707) 972 2918 | Other | Hopland · Mendocino County | — | — |
| Curnutt Construction | Billy Franklin Curnutt | — | (707) 272 5806 | Other | Redwood Valley · Mendocino County | — | — |
| Curran Construction | Michael Joseph Curran | — | (707) 328 6415 | GC, remodel, ADU | Point Arena · Mendocino County | — | — |
| Current Energy Solutions | Current Energy Solutions | — | (707) 357 7149 | Electricians | Willits · Mendocino County | — | — |
| Curt Gordon Heating - Cooling | Curt Gordon Heating - Cooling | — | (707) 489 8700 | HVAC | Ukiah · Mendocino County | — | — |
| Custom Heating And Cooling | Custom Heating And Cooling | — | (707) 272 4990 | HVAC | Redwood Valley · Mendocino County | — | — |