| Bg Backflow Services | Bryan James Guntle | — | (707) 696 7010 | Other | Rohnert Park · Sonoma County | — | — |
| Bianchi Mechanical | Bianchi Mechanical | — | (707) 848 1577 | HVAC | Santa Rosa · Sonoma County | — | — |
| Bielefield Construction INC | Raymond Patrick Bielefield | bielefieldconstruction@yahoo.com | (415) 250 9412 | GC, remodel, ADU | Rohnert Park · Sonoma County | — | — |
| Big Al's Heating & Air LLC | Vijay Eknath Ambavanekar | — | (805) 427 6021 | HVAC | Santa Rosa Valley · Sonoma County | — | — |
| Big Al's Plumbing | Alan Bauermeister | bigalsplumbing1@gmail.com | (369) 777 0075 | Other | Sonoma · Sonoma County | — | — |
| Big Apple Construction Group INC | Yaron Palfy | — | (415) 578 8227 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Big G Lcarillo Construction | Carrillo German Lopez | — | (707) 294 9129 | GC, remodel, ADU | Sonoma · Sonoma County | — | — |
| Big O'floor Coverings INC | Otnit Arellano-Barajas | — | (707) 953 2099 | Other | Santa Rosa · Sonoma County | — | — |
| Big River Builders INC | Michael Paul Boese | — | (707) 290 3610 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Bigham Home Services | Paul William Bigham | — | (707) 975 9588 | HVAC | Windsor · Sonoma County | — | — |
| Bill Ayers Drapery Installations | Bill Ayers Drapery Installations | — | (707) 287 5396 | Other | Sonoma · Sonoma County | — | — |
| Bill Cileo | Bill Cileo | — | (707) 479 1501 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Bill Kutz Heating & Air Conditioning INC | William Robert Kutz | — | (707) 623 9814 | HVAC | Santa Rosa · Sonoma County | — | — |
| Bill Moritz Construction Services | William Steven Moritz | — | (707) 708 9616 | GC, remodel, ADU | Cotati · Sonoma County | — | — |
| Bill Rummonds & Associates INC DBA Purofirst Of Sonoma County | Ryan Newton Rummonds | — | (707) 538 1772 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Bill Yeo Electric INC | Sasha Marc Makiva | impallari@gmail.com | (707) 935 1150 | Electricians | Sonoma · Sonoma County | — | — |
| Billy Alberigi | Billy Alberigi | — | (707) 874 1839 | Other | Occidental · Sonoma County | — | — |
| Biltmore Builders INC | Guy William Parsons | — | (707) 843 7405 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Binkley Electric | Donald Glenn Binkley | — | (707) 576 7004 | Electricians | Santa Rosa · Sonoma County | — | — |
| Biogas Energy INC | Brian Charles Gannon | — | (707) 888 4316 | Other | Sebastopol · Sonoma County | — | — |
| Birdhouse Electric INC | Blake Anderson Gruetter | — | (707) 337 9631 | Electricians | Santa Rosa · Sonoma County | — | — |
| Birdseye Builders INC | Joseph Michael Hicks | — | (415) 317 7008 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Biss Construction INC | Matthew Brian Biss | — | (707) 490 5291 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Biswell Forestry LLC | Marisa Sue Evans | — | (925) 325 3502 | Tree | Cazadero · Sonoma County | — | — |
| Bj Painting | Bj Painting | — | (707) 758 1864 | Windows, patio, painters | Windsor · Sonoma County | — | — |
| Bkb Heating Air Conditioning & Sheet Metal | Brian Keith Butts | — | (707) 769 9655 | HVAC | Petaluma · Sonoma County | — | — |
| Bkd Painting INC | Brent David Baumunk | — | (360) 702 9705 | Windows, patio, painters | Healdsburg · Sonoma County | — | — |
| Black Arrow Construction | Mario Leon Rojas | — | (707) 328 3455 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Black Dog Electric INC | Scott Wallis Farnsworth | — | (707) 696 3647 | Electricians | Windsor · Sonoma County | — | — |
| Black Dog Excavation | John David Merget | — | (916) 501 8081 | Other | Santa Rosa · Sonoma County | — | — |
| Black Iron INC | Ronnie Frank Black | info@blackiron.com | (707) 473 9403 | Other | Healdsburg · Sonoma County | — | — |
| Black Oak Builders Incorporated | Andrew Constentino Briglio | — | (707) 823 2625 | GC, remodel, ADU | Sebastopol · Sonoma County | — | — |
| Black Oak Canyon INC | Dennis Kevin Reynolds | dennis@blackoakcanyon.com | (707) 494 6301 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Black Oak Landscape | Black Oak Landscape | — | (707) 230 4830 | Windows, patio, painters | Petaluma · Sonoma County | — | — |
| Black Oak Tree Care | Black Oak Tree Care | — | (707) 230 8285 | Other | Sonoma · Sonoma County | — | — |
| Black Point Excavation | Von Schalscha Craig | — | (707) 280 9559 | Other | Petaluma · Sonoma County | — | — |
| Black Sun Boilers INC | Christopher John Doble | chris@blacksunboilers.com | (415) 310 7540 | HVAC | Santa Rosa · Sonoma County | — | — |
| Blackstone Homes INC | Gregory Joel Lucas | — | (707) 526 3565 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Blaisdell Construction | Philip Zahl Ii Blaisdell | craig@blaisdellconstruction.com | (707) 933 7697 | GC, remodel, ADU | Santa Rosa · Sonoma County | — | — |
| Blakeslee Electric INC | Adam John Hansen | — | (707) 545 6393 | Electricians | Santa Rosa · Sonoma County | — | — |