| John T Campbell | John T Campbell | — | (415) 845 7501 | Windows, patio, painters | Sebastopol · Sonoma County | — | — |
| John Thompson Enterprises Partnership | John Edward Thompson | — | (775) 846 4573 | Other | Windsor · Sonoma County | — | — |
| John Vermeulen Building & Fencing | John Vermeulen Building & Fencing | — | (707) 481 4157 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| John W Flaherty Construction Co | John Ward Flaherty | — | (415) 699 5340 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| John Whelan Floorcovering | John Whelan Floorcovering | — | (707) 540 1756 | Other | Rohnert Park · Sonoma County | — | — |
| John's Formica INC | John Raymond Deas | — | (707) 544 8585 | Other | Santa Rosa · Sonoma County | — | — |
| Johnny's Electric | John Gabriel Lucatero | — | (707) 343 6701 | Electricians | Sonoma · Sonoma County | — | — |
| Johnson Electric | Dustin James Johnson | — | (707) 889 3870 | Electricians | Santa Rosa · Sonoma County | — | — |
| Johnson Electric & Shades | Nicholas Ryan Johnson | — | (707) 478 1932 | Electricians | Santa Rosa · Sonoma County | — | — |
| Johnson Electrical | Robert Bruce Johnson | — | (707) 235 4530 | Electricians | Rohnert Park · Sonoma County | — | — |
| Johnson Pools INC | Aaron Wayne Johnson | — | (707) 837 0604 | Pool | Windsor · Sonoma County | — | — |
| Johnston Sign Company INC | Todd Gardner Johnston | — | (707) 829 7332 | Other | Petaluma · Sonoma County | — | — |
| Jon Ballard Construction | Jon Christian Jr Ballard | jon@jonballardconstruction.com | (707) 337-8021 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Jon Ray & Sons Construction | Jon Webster Jr Ray | — | (707) 996 9174 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Jon Smith Construction | Jonathan Walter Smith | — | (707) 696 1960 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Jonathan Abel Restorations | Jonathan Abel Restorations | — | (707) 541 8680 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Jonathan Dougall INC | Jonathan Bellamy Dougall | — | (510) 220 2514 | Electricians | Sebastopol · Sonoma County | — | — |
| Jonathan Stoumen Engineering | Jonathan Stoumen Engineering | — | (707) 293 6801 | Other | Sebastopol · Sonoma County | — | — |
| Jones Builders | Jones Builders | — | (707) 975 6389 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Jones Drywall INC | Richard Allen Jones | — | (707) 217 0085 | Other | Cloverdale · Sonoma County | — | — |
| Jones Electric | Robert Sumner Jr Jones | — | (707) 765 2972 | Electricians | Petaluma · Sonoma County | — | — |
| Jones Garage Door Company Incorporated | William L Iii Wright | — | (707) 795 5426 | Other | Petaluma · Sonoma County | — | — |
| Jordan Const | Jordan Const | — | (707) 332 1993 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Jordan Construction | Joel Anthony Jordan | — | (707) 696 3086 | GC, remodel, ADU | Penngrove · Sonoma County | — | — |
| Jordan Edwards Flooring & Carpet | Jordan Edwards Flooring & Carpet | — | (707) 393 7861 | Other | Sebastopol · Sonoma County | — | — |
| Jorgensen Construction | James Stack Jorgensen | — | (707) 292 0421 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Jose Esparza Fence | Jose Esparza Fence | — | (707) 484 3437 | Other | Santa Rosa · Sonoma County | — | — |
| Joseph A Perrault | Joseph A Perrault | — | (415) 378 4871 | Windows, patio, painters | Cotati · Sonoma County | — | — |
| Joseph Allen Painting | Joseph Allen Painting | — | (707) 326 8041 | Windows, patio, painters | Santa Rosa · Sonoma County | — | — |
| Joseph F Merz | Joseph F Merz | — | (707) 938 9232 | GC, remodel, ADU | Glen Ellen · Sonoma County | — | — |
| Joseph J Railla | Joseph J Railla | — | (415) 637 9698 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Joseph Paul Painting | Joseph Paul Painting | joeyscoatings@hotmail.com | (707) 931 8881 | Windows, patio, painters | Cotati · Sonoma County | — | — |
| Joseph T Callinan Construction INC | Joseph Timothy Callinan | — | (707) 585 3277 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| Joseph Washington Price | Joseph Washington Price | — | (310) 308 8715 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| Josephs Plumbing Service | Joseph Ronald Fornaciari | judy@advergraphics.com | (707) 823 6417 | Other | Sebastopol · Sonoma County | — | — |
| Josh Begin Construction | Begin Joshua | — | (707) 690 2541 | Electricians | Santa Rosa · Sonoma County | — | — |
| Josh Chandler Construction INC | Josh Allen Chandler | — | (707) 480 8935 | GC, remodel, ADU | Cloverdale · Sonoma County | — | — |
| Josh Woods Construction LLC | Joshua Patrick Woods | — | (707) 321 2263 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Joshua Schainblatt | Joshua Schainblatt | — | (707) 537 5839 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Josski Plumbing | Josski Plumbing | — | (707) 503 8516 | Other | Sebastopol · Sonoma County | — | — |