| John Danpour | John Danpour | — | (925) 210 1600 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| John David Construction | John David Gardner | — | (925) 395 8700 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| John Decesare Construction | John Michael Decesare | — | (925) 383 6897 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| John Edmunds INC DBA J P Electric | John Patrick Edmunds | — | (510) 741 5504 | Electricians | Crockett · Contra Costa County | — | — |
| John Edward Gallagher | John Edward Gallagher | — | (925) 376 7399 | Other | Martinez · Contra Costa County | — | — |
| John Fitzpatrick | John Fitzpatrick | — | (925) 765 3974 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| John G Larson DBA J G L Construction | John Grant Larson | — | (925) 708 3025 | GC, remodel, ADU | Pleasant Hill · Contra Costa County | — | — |
| John Gregory Dower | John Gregory Dower | — | (415) 515 3142 | GC, remodel, ADU | El Cerrito · Contra Costa County | — | — |
| John I Cooper General Contractor INC | John Ira Sr Cooper | — | (408) 590 8377 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| John Illish | John Illish | — | (925) 872 8869 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| John K Ilyin | John K Ilyin | — | (415) 297 2055 | GC, remodel, ADU | Kensington · Contra Costa County | — | — |
| John M Pluff | John M Pluff | — | (408) 316 5553 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| John Mc Donald | John Mc Donald | — | (925) 768 3016 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| John Mc Lean Construction | John Patrick Mc Lean | — | (925) 297 9143 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| John Morrison INC | Tai Dao Huynh | — | (510) 655 5404 | HVAC | Lafayette · Contra Costa County | — | — |
| John Porter | John Porter | — | (925) 595 0366 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| John Protopappas | John Protopappas | — | (510) 452 2944 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| John Rose Drywall | John Rose Drywall | — | (925) 640 6844 | Other | Concord · Contra Costa County | — | — |
| John Ross Howe Construction | John Ross Howe | — | (510) 215 5134 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| John S Kinstle | John S Kinstle | — | (510) 882 9927 | GC, remodel, ADU | El Sobrante · Contra Costa County | — | — |
| John Schulze Construction | John Richard Schulze | — | (925) 639 6241 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| John Timothy Krause DBA Wallpaper Solutions | Wallpaper Solutions | — | (925) 691 4944 | Other | Concord · Contra Costa County | — | — |
| John Weaver | John Weaver | — | (925) 200 0015 | Electricians | Pleasant Hill · Contra Costa County | — | — |
| Johnathan R Rossi Construction | Jonathan Ray Rossi | — | (925) 457 7163 | GC, remodel, ADU | Alamo · Contra Costa County | — | — |
| Johnny George Painting & Decorating INC | Johnny Gregory George | — | (925) 946 0828 | Windows, patio, painters | Concord · Contra Costa County | — | — |
| Johnson Mechanical LLC | Keith Eugene Johnson | johnson@johnson-mechanical.com | (925) 648 9506 | Pool | Danville · Contra Costa County | — | — |
| Johnson's Flooring | Johnson's Flooring | — | (925) 324 4967 | Other | Antioch · Contra Costa County | — | — |
| Jolcron Builders INC | Ceron Jimenez Joel | — | (415) 816 8031 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Jolly Steel Company INC | Stephen Christopher Jolly | — | (925) 260 0313 | Other | Concord · Contra Costa County | — | — |
| Jon Beltrami | Jon Beltrami | — | (707) 342 9198 | GC, remodel, ADU | Pinole · Contra Costa County | — | — |
| Jon Blair Painting | Jon Blair Painting | — | (510) 882 4467 | Windows, patio, painters | Pleasant Hill · Contra Costa County | — | — |
| Jon Walser Construction INC | Jon Scott Walser | — | (925) 872 3159 | GC, remodel, ADU | Discovery Bay · Contra Costa County | — | — |
| Jonathan Chaparro Construction | Jonathan Albert Chaparro | — | (925) 297 9314 | GC, remodel, ADU | Lafayette · Contra Costa County | — | — |
| Jonathan King | Jonathan King | — | (925) 408 9029 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Jonathan Koutsohanos | Jonathan Koutsohanos | — | (925) 471 1601 | GC, remodel, ADU | Martinez · Contra Costa County | — | — |
| Jonathan Tower Construction | Jonathan Todd Tower | — | (510) 912 0692 | GC, remodel, ADU | Richmond · Contra Costa County | — | — |
| Jones Floor Designs | Jones Floor Designs | — | (925) 584 9592 | Other | Antioch · Contra Costa County | — | — |
| Jong D Lee | Jong D Lee | — | (925) 348 3399 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Jordan Drapery & Blinds | Jordan Drapery & Blinds | — | (510) 734 7864 | Other | Pinole · Contra Costa County | — | — |
| Jordan Electric | John Chase Jordan | info@jordanelectric.com | (510) 757 8800 | Electricians | Richmond · Contra Costa County | — | — |