| Chelsea General Contractors INC | Jesus Osmany Garcia | info@chelseageneralcontractors.com | (707) 367 2169 | GC, remodel, ADU | Upper Lake · Lake County | — | — |
| Chernoh Excavating INC | Joshua Isaac Chernoh | — | (707) 995 1359 | Other | Lower Lake · Lake County | — | — |
| Chris Moe | Chris Moe | — | (707) 349 3534 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Cl Construction | Chris Clovis Legue | — | (510) 773 1740 | GC, remodel, ADU | Lucerne · Lake County | — | — |
| Classic Home Improvements | Classic Home Improvements | — | (858) 224-7373 | GC, remodel, ADU | Escondido · Lake County | — | — |
| Clifton Security Systems | Clifton Security Systems | — | (707) 328 6171 | Electricians | Lakeport · Lake County | — | — |
| Cm Builders LLC | Pina Cesar Chavez | — | (415) 859 6042 | GC, remodel, ADU | Clearlake · Lake County | — | — |
| Cm Electric | Carlos Emmanuel Montes-Mercado | reception@cmelectric.com | (707) 295 7168 | Electricians | Middletown · Lake County | — | — |
| Coastal Mountain Electric | Susan Elizabeth Stone | — | (707) 994 0437 | Electricians | Lower Lake · Lake County | — | — |
| Coleman Construction LLC | Tracy Allen Coleman | — | (707) 275 9016 | Other | Upper Lake · Lake County | — | — |
| Coleman Plumbing | Coleman Plumbing | — | (707) 292 4262 | Other | Lakeport · Lake County | — | — |
| Colemans Custom Construction | Toby James Coleman | — | (707) 349 4070 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Colin Construction LLC | Oscar Ruben Colin | — | (707) 264 9406 | GC, remodel, ADU | Lakeport · Lake County | — | — |
| Comfortable Living HVAC | Comfortable Living HVAC | — | (707) 367 0946 | HVAC | Lower Lake · Lake County | — | — |
| Concha Construction | Raul Vega Concha | raul@concha-construction.com | (707) 350 5937 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| Conover Electric | Brian Garrett Conover | — | (707) 533 3590 | Electricians | Hidden Valley Lake · Lake County | — | — |
| Cool Air Conditioning & Heating INC | Michael James Huber | — | (707) 245 7332 | HVAC | Kelseyville · Lake County | — | — |
| Cooper Construction | Ralph L Cooper | — | (707) 263 1932 | GC, remodel, ADU | Lakeport · Lake County | — | — |
| Cornerstone Cabinets | Cornerstone Cabinets | — | (760) 937 0826 | GC, remodel, ADU | Lakeport · Lake County | — | — |
| Cory Benjamen Moore | Cory Benjamen Moore | — | (707) 721 7984 | GC, remodel, ADU | Clear Lake · Lake County | — | — |
| Coulter Construction | Jeff Eugene Coulter | — | (707) 350 1980 | GC, remodel, ADU | Lower Lake · Lake County | — | — |
| Country Carpets | Country Carpets | — | (707) 275 2000 | Other | Upper Lake · Lake County | — | — |
| Coyote Valley Construction Co | Michael Henry Sand | — | (707) 355 1104 | GC, remodel, ADU | Hidden Valley Lake · Lake County | — | — |
| Cr United Construction INC | Rodriguez Francisco Cervantes | — | (707) 287 1072 | GC, remodel, ADU | Middletown · Lake County | — | — |
| Craft Built Construction | Jacob Paul Rich | — | (707) 905 7597 | GC, remodel, ADU | Cobb · Lake County | — | — |
| Crail Construction | Johnny Ray Crail | — | (707) 321 3463 | GC, remodel, ADU | Hidden Valley Lake · Lake County | — | — |
| Cramer Enterprises | Eric Jason Cramer | — | (707) 349 8575 | Other | Lakeport · Lake County | — | — |
| Criss Tree Care | Criss Tree Care | — | (707) 349 2113 | Tree | Lakeport · Lake County | — | — |
| Cross Cut Construction | Brian Taylor Swaney | — | (707) 275 9247 | GC, remodel, ADU | Upper Lake · Lake County | — | — |
| Cruz Brothers INC | Gerardo G Cruz | — | (707) 501 8285 | Windows, patio, painters | Middletown · Lake County | — | — |
| Cruz Concrete | Cruz Concrete | — | (707) 245 0229 | Other | Nice · Lake County | — | — |
| Curtis Edwards Roofing & Seamless Gutters INC | Curtis Everett Edwards | — | (707) 900 1517 | Other roofers | Middletown · Lake County | — | — |
| D & D Fence | D & D Fence | — | (707) 275 0182 | Other | Upper Lake · Lake County | — | — |
| D & T Electric INC | Vincent William Iii Tufo | impallari@gmail.com | (707) 795 7779 | Electricians | Middletown · Lake County | — | — |
| D And K Engineering | Derek Loren Desoto | — | (707) 355 0205 | Other | Middletown · Lake County | — | — |
| D Cruz Construction INC | Cruz Daniel | daniel@dcruzconstruction.com | (707) 802 4006 | GC, remodel, ADU | Lower Lake · Lake County | — | — |
| D G Construction | Gomora-hernandez Daniel | — | (707) 349 3736 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| D Hoskins Enterprises DBA Heritage Builders | Lester Dale Jr Hoskins | — | (707) 987 7378 | GC, remodel, ADU | Middletown · Lake County | — | — |
| D R Goebel Construction | Dale Randall Goebel | — | (707) 349 9465 | GC, remodel, ADU | Kelseyville · Lake County | — | — |
| D S Concrete INC | Dale Francis Soditus | — | (707) 350 2243 | Other | Clearlake · Lake County | — | — |