| C D H Construction | Chris Daniel Hampton | — | (707) 328 5399 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| C D K Builders | C D K Builders | — | (415) 481 5544 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| C D M Builders INC | Christopher Gregory Means | — | (707) 478 5793 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| C E Construction | Ciaran George Eustace | — | (707) 694 9269 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| C E L Construction | Craig Edward Larson | — | (707) 494 1197 | GC, remodel, ADU | Healdsburg · Sonoma County | — | — |
| C F Dreyer Co | Carl Frederick Dreyer | — | (707) 829 7216 | Windows, patio, painters | Sebastopol · Sonoma County | — | — |
| C G M Flooring | C G M Flooring | — | (707) 235 3311 | Other | Santa Rosa · Sonoma County | — | — |
| C H Painting Co | Christopher Lee Hansen | — | (707) 326 4074 | Windows, patio, painters | Healdsburg · Sonoma County | — | — |
| C Hand Electric INC | Christopher Stephen Hand | — | (808) 640 6595 | Electricians | Penngrove · Sonoma County | — | — |
| C Hardy General Engineering Contractor INC | Cory Michael Hardy | — | (707) 765 9157 | Other | Petaluma · Sonoma County | — | — |
| C J Electric | Christopher Crayton Jones | — | (707) 328 8599 | Electricians | El Verano · Sonoma County | — | — |
| C J Reed Construction Co | Christopher Jon Reed | — | (707) 769 7241 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| C J Sullivan Electric | Chris John Sullivan | — | (650) 954 5043 | Electricians | Cloverdale · Sonoma County | — | — |
| C J's Iron Fence LLC | Charles Fredrick Fagan | — | (707) 838 9794 | Other | Windsor · Sonoma County | — | — |
| C Jack Hervey Construction | Chad Jack Hervey | — | (808) 936 5318 | GC, remodel, ADU | Forestville · Sonoma County | — | — |
| C L Marshall Company DBA Marshall Scaffold & Supply | Chad Edward Miller | — | (707) 542 0464 | Other | Santa Rosa · Sonoma County | — | — |
| C L Richeson Custom Builders | C L Richeson Custom Builders | — | (707) 774 9167 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| C L Y Incorporated DBA Sonoma-marin Construction | Richard Charles Young | — | (707) 763 6981 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| C Lopez Enterprises INC | Hernandez Cesar Lopez | — | (707) 322 9696 | Other roofers | Santa Rosa · Sonoma County | — | — |
| C Lopez Yard Maintenance | C Lopez Yard Maintenance | info@clopezyardmaintenance.com | (707) 545 9234 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| C M Taylor Electric | Chad Mitchell Taylor | info@cmtaylorelectric.com | (707) 490 8725 | Electricians | Petaluma · Sonoma County | — | — |
| C M Taylor Electrical Contractors INC | Chad Mitchell Taylor | — | (707) 490 8825 | Electricians | Petaluma · Sonoma County | — | — |
| C Merz Excavating & Grading INC | Clint Robert Merz | — | (707) 888 9704 | Other | Petaluma · Sonoma County | — | — |
| C N C Electric | Christopher James Nielsen | — | (707) 688 8561 | Electricians | Petaluma · Sonoma County | — | — |
| C N S Mechanical INC | Stephen Suby Sankoff | — | (707) 776 4552 | HVAC | Petaluma · Sonoma County | — | — |
| C P Hardwood Flooring | C P Hardwood Flooring | — | (707) 236 5481 | Other | Santa Rosa · Sonoma County | — | — |
| C S G Building & Remodeling | Camilo Souza Gomes | — | (707) 241 6000 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| C V Larsen Co | Christopher Vaugh Larsen | clarsen@cvlarsen.com | (707) 526 3750 | Other | Santa Rosa · Sonoma County | — | — |
| C W Mechanical | C W Mechanical | — | (707) 775 9088 | Other | Cloverdale · Sonoma County | — | — |
| C&m Drywall Services | Gabriela Leticia Caach Medina | — | (707) 623 6201 | Other | Windsor · Sonoma County | — | — |
| C&m Tree Care Corp | Christopher Barrientos | cmtreecare2023@outlook.com | (707) 805 2928 | Other | Santa Rosa · Sonoma County | — | — |
| C6b Incorporated | Noel Michael O'keeffe | — | (510) 316 8654 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Caballero's Plumbing | Caballero's Plumbing | — | (707) 787 7597 | Other | Rohnert Park · Sonoma County | — | — |
| Cabinet Shop | Cabinet Shop | — | (707) 494 6647 | Other | Santa Rosa · Sonoma County | — | — |
| Cabot And Company | Jeffrey Harris Cabot | — | (510) 910 3772 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| Caiati Customs INC | Kristopher James Caiati | — | (707) 775 4360 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Cal Construction Expert Company | David Td Nguyen | — | (707) 889 1213 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Cal Floors & Floor Covering Contractor | Vincent Ruiz Sierras | — | (415) 533 7580 | Other | Petaluma · Sonoma County | — | — |
| Cal Saving Construction | Romero Cruz Rigoberto | — | (707) 326 8294 | GC, remodel, ADU | Windsor · Sonoma County | — | — |
| Cal Scapes Landscape Maintenance | Cal Scapes Landscape Maintenance | — | (707) 308 8882 | Windows, patio, painters | Graton · Sonoma County | — | — |