| K & M Construction | Kambiz Haghighatasbagh | — | (415) 412 6083 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| K & M Electric | William John Needham | — | (925) 864 0929 | Electricians | Discovery Bay · Contra Costa County | — | — |
| K & R Heating And Air Conditioning Service | Raul Fernando Valderrama | — | (925) 798 5088 | HVAC | Concord · Contra Costa County | — | — |
| K & R Heating And Cooling Service INC | Kevin Raoul Valderrama | — | (925) 400 5195 | HVAC | Concord · Contra Costa County | — | — |
| K B Stone Diamond Corporation | Keith Brian Stone | — | (925) 934 2711 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| K Bali Construction INC | Kevin Salvatore Balestrieri | — | (925) 478 8182 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| K C Custom Builders | K C Custom Builders | — | (510) 706 9063 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| K C Flooring Specialist INC | Carlos Guillermo Quintanilla | — | (510) 260 4599 | Other | San Pablo · Contra Costa County | — | — |
| K C L General Contractor | K C L General Contractor | — | (415) 676 0546 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| K C Wilson Plumbing INC DBA Wilson Plumbing | James Kirk Wilson | — | (925) 228 8171 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| K D M Builders INC | Michael Wray Huffaker | — | (925) 383 7943 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| K K C Structural & Building Construction | Chung Kin Keung | — | (415) 867 5917 | GC, remodel, ADU | Bay Point · Contra Costa County | — | — |
| K M C Design Group INC DBA K M C Plumbing Co | Michael Joseph Buckley | — | (925) 382 6764 | Other | Danville · Contra Costa County | — | — |
| K M D Construction | Mehrabadi Keyvan | — | (510) 435 4415 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| K M S Glass LLC | Malik Hamidani | contact@kmsglass.com | (510) 508 9761 | Windows, patio, painters | El Sobrante · Contra Costa County | — | — |
| K O D Construction Incorporated | Kevin Joseph O'donoghue | — | (415) 678 7141 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| K O Floors | Silbestre Andres Callejas Martinez | — | (925) 726 6784 | Other | Pittsburg · Contra Costa County | — | — |
| K R Design And Construction | Ramirez Kent | — | (925) 518 4966 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| K R Electric INC | Kevin Russell Rushing | — | (925) 487 3070 | Electricians | San Ramon · Contra Costa County | — | — |
| K S Kruse | K S Kruse | — | (925) 427 5547 | Other | Pittsburg · Contra Costa County | — | — |
| K Y Electric | Kevin Raoul Young | — | (510) 235 3600 | Electricians | San Pablo · Contra Costa County | — | — |
| K&i Electrical LLC | Iain Searle | ki@kielectrical.com | (925) 913 9383 | Electricians | San Ramon · Contra Costa County | — | — |
| K&k Jl Services INC DBA K&k Construction | Hementh Dutt Sharma | — | (510) 209 0742 | Electricians | Concord · Contra Costa County | — | — |
| K-1 Interlocking Pavers | Leticia Cristina Ribeiro Da Silva | — | (510) 322 0319 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Kab Painting | Kab Painting | — | (510) 301 0157 | Windows, patio, painters | San Ramon · Contra Costa County | — | — |
| Kacyra Construction | Joseph K Kacyra | — | (925) 525 2939 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Kaifa Construction INC | Li Geng Zheng | — | (415) 518 6078 | GC, remodel, ADU | San Pablo · Contra Costa County | — | — |
| Kaljian Construction INC | Robert Vaughn Kaljian | — | (925) 383 2947 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Kamal Construction | Kamaljit Singh Khangura | — | (510) 468 9008 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Kambiz Moafi | Kambiz Moafi | — | (925) 383 1494 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Kaminski Floors | Kaminski Floors | — | (510) 325 3275 | Other | Martinez · Contra Costa County | — | — |
| Karl J Schultz Construction | Karl Jerome Schultz | — | (925) 408 1593 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Karl M Kyrklund | Karl M Kyrklund | — | (415) 690 9666 | Other | Pinole · Contra Costa County | — | — |
| Karl Mulligan | Karl Mulligan | — | (510) 215 2290 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| Karl Whitehead | Karl Whitehead | — | (925) 787 8171 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| Kasas Builders INC | Fernando Jose Martinez Bustillo | — | (415) 410 7456 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| Kasten Builders | Peter John Kasten | — | (415) 897 4500 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Kat Electric Service INC | Kip Allen Trombley | — | (925) 285 5118 | Electricians | Bay Point · Contra Costa County | — | — |
| Katarzyna Wojtunik | Katarzyna Wojtunik | — | (925) 768 8323 | Windows, patio, painters | Antioch · Contra Costa County | — | — |
| Kato Plumbing | Kato Plumbing | — | (510) 684 2531 | Other | Richmond · Contra Costa County | — | — |