| Katona Tile | Katona Tile | — | (925) 727 9366 | Other | Brentwood · Contra Costa County | — | — |
| Kaufman Construction INC | Martin Louis Kaufman | — | (510) 848 4000 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Kaufman Home Improvement | Kaufman Home Improvement | — | (925) 382 0739 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Kautch INC DBA White's Electric Service | Richard Anthony Kautch | — | (510) 773 9283 | Electricians | Concord · Contra Costa County | — | — |
| Kazemi Construction | Kazemidastjerdehei Mehdi | — | (925) 888 9949 | GC, remodel, ADU | Danville · Contra Costa County | — | — |
| Kazzaz Landscaping | Kazzaz Landscaping | — | (925) 516 7270 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Kb Security Kams INC | Kyndl Steve Buzas | — | (925) 890 0790 | Alarm and generators | Oakley · Contra Costa County | — | — |
| Kbd's Electric | David Paul Tooker | — | (925) 550 1948 | Electricians | Concord · Contra Costa County | — | — |
| Kbj Remodels | Kbj Remodels | — | (415) 272 0636 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Kc Calderon Construction | Carlos Enrique Calderon Diaz | — | (510) 406 5654 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Kc Construction | Kirby Lloyd Hughes | — | (510) 778 5623 | GC, remodel, ADU | Hercules · Contra Costa County | — | — |
| Kc Pool Services | Kurtis Lynn Cockrum | info@kcpoolservices.com | (925) 457 5339 | Pool | Walnut Creek · Contra Costa County | — | — |
| Kcctech LLC | Hakan Kavlak | info@kcctech.com | (628) 400 2420 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Kck Construction & Remodeling LLC | Kevin Ernesto Vasquez | — | (510) 978 3259 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Kd Bros Concrete INC | Galindo Brablio Rivas | — | (415) 259 8431 | Other | Richmond · Contra Costa County | — | — |
| Keding DBA K Floors | Reggie Alan Keding | — | (925) 350 4200 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Keeney H V A C | Keeney H V A C | — | (925) 628 6635 | HVAC | Antioch · Contra Costa County | — | — |
| Keez Construction INC | Elyas Redae Kefela | — | (650) 516 8339 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Keith Haisley Construction | Keith David Haisley | — | (925) 216 4793 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| Keith Roueche | Keith Roueche | — | (510) 685 7220 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Kel-aire | Janis Irene Baldwin | — | (510) 245 4140 | HVAC | Rodeo · Contra Costa County | — | — |
| Keller Electric | Steven John Keller | — | (925) 684 0230 | Electricians | Bethel Island · Contra Costa County | — | — |
| Kellman Construction LLC | Benjamin Ivan Kellman | — | (510) 620 9600 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Kelly And Son | Venson Joseph Kelly | — | (925) 487 4935 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Kelly And Son LLC | Kenneth Erwin Kelly | — | (925) 487 4935 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Kelly Construction | Leo Victor Kelly | — | (925) 405 2394 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Kelly Electric INC | Brian Edward Kelly | — | (925) 360 0794 | Electricians | Danville · Contra Costa County | — | — |
| Kelly Indoor Comfort Systems | Kelly Indoor Comfort Systems | — | (925) 766 5844 | HVAC | Martinez · Contra Costa County | — | — |
| Kelly Plumbing | Kelly Plumbing | interested@domainmarket.com | (925) 322 9672 | Other | Concord · Contra Costa County | — | — |
| Kemper Development Kompany | Kemper Development Kompany | — | (925) 997 2098 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Ken Lun Chan | Ken Lun Chan | — | (415) 504 2388 | Electricians | Orinda · Contra Costa County | — | — |
| Ken Mitolo Construction | Kenneth David Mitolo | — | (925) 672 2460 | GC, remodel, ADU | Clayton · Contra Costa County | — | — |
| Ken Prine Construction | Ron Kenneth Prine | — | (925) 260 4567 | GC, remodel, ADU | Discovery Bay · Contra Costa County | — | — |
| Ken The Painter | Ken The Painter | — | (925) 822 8075 | Windows, patio, painters | Martinez · Contra Costa County | — | — |
| Ken Wolf Tile And Construction | Kenneth John Wolf | — | (408) 594 3466 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Kenco Construction | Kenneth Lawrence Habiger | — | (925) 872 1831 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Kendall Dean Patterson Construction | Kendall Dean Patterson | — | (510) 304 2423 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Kennedy Spa Service | Fred Everett Iv Kennedy | — | (925) 250 4589 | Pool | Martinez · Contra Costa County | — | — |
| Kenneth Ferrante | Kenneth Ferrante | — | (925) 778 3939 | Other | Knightsen · Contra Costa County | — | — |
| Kenneth Jordan Construction | Kenneth Charles Dippo | — | (925) 595 8606 | GC, remodel, ADU | Concord · Contra Costa County | — | — |