| 3G Plumbing INC | Fuentes Daniel Casillas | — | (760) 234 2494 | Other | Indio · Riverside County | — | — |
| 3G Rebar INC | John Michael Dean | — | (661) 588 0294 | Other | Bakersfield · Kern County | — | — |
| 3g's Roofing Corp | Luis Enrique Garcia | — | (714) 650 2096 | Other roofers | Santa Ana · Orange County | — | — |
| 3gen Contractors | Armando Velazquez | — | (909) 631 4355 | GC, remodel, ADU | Riverside · Riverside County | — | — |
| 3gen Resurfacing LLC | Lance Adam Johnson | — | (916) 919 7776 | Other | Chico · Butte County | — | — |
| 3gm Builders | Sergio Madrigal | — | (949) 705 9059 | GC, remodel, ADU | Corona · Riverside County | — | — |
| 3gm Construction | Miranda-duran Gerardo | enquiry@3gmconstruction.com | (949) 813 7620 | GC, remodel, ADU | San Juan Capistrano · Orange County | — | — |
| 3H Builders | Clayton Karyen Wu | — | (415) 519 2106 | GC, remodel, ADU | San Francisco · San Francisco County | — | — |
| 3H Demolition Contracting Services INC | Hector Manuel Alvarado | — | (909) 223 1850 | Other | Whittier · Los Angeles County | — | — |
| 3H Electric INC | Hugo Andres Sanchez | — | (760) 879 8370 | Electricians | Imperial · Imperial County | — | — |
| 3in1 Control INC | Michael Dwayne Spencer | — | (916) 496 6701 | HVAC | West Sacramento · Yolo County | — | — |
| 3ix Construction INC | Peter John Van Der Veen | — | (408) 863 2011 | GC, remodel, ADU | Citrus Heights · Sacramento County | — | — |
| 3J Company | James Joseph Ongaro | — | (951) 588 7277 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| 3J Construction | Sandy Orquiza Alvarez | impallari@gmail.com | (415) 794 0225 | GC, remodel, ADU | Daly City · San Mateo County | — | — |
| 3J Construction LLC | Joseph Adel Zaky | impallari@gmail.com | (714) 402 7550 | GC, remodel, ADU | La Habra · Orange County | — | — |
| 3J Restoration LLC | Guillermo Rubio | — | (760) 890 5454 | GC, remodel, ADU | Calexico · Imperial County | — | — |
| 3J Stucco | Franklin Giovanni Ventura | — | (213) 364 7282 | Other | Los Angeles · Los Angeles County | — | — |
| 3J Tile INC | Jose Roberto Juarez | — | (650) 399 6819 | Other | San Carlos · San Mateo County | — | — |
| 3jc Construction INC DBA Oc Flooring | Byung Kil Kim | — | (909) 896 8467 | GC, remodel, ADU | Irvine · Orange County | — | — |
| 3js Construction INC | Jose D Jacobo | buildzoomsupport@blockrenovation.com | (858) 688 8247 | GC, remodel, ADU | San Diego · San Diego County | — | — |
| 3js Electric | Jeremy Frederic Thomas-sanchez | — | (916) 599 9791 | Electricians | Elk Grove · Sacramento County | — | — |
| 3lite Construction INC | Uriel A Rodriguez Silva | — | (714) 200 7530 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| 3lm Pool And Spa INC | Cruz Lazaro Merino Pioquinto | — | (818) 389 5771 | Pool | Sylmar · Los Angeles County | — | — |
| 3M Building & Development INC | Adam Keeling Macon | — | (818) 970 6596 | GC, remodel, ADU | Tarzana · Los Angeles County | — | — |
| 3M Construction Company | Michael Steven Massoletti | — | (415) 308 2911 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| 3M Construction Corporation | Mahmoud Anis Merzi | — | (949) 898 9595 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| 3M Flooring INC | Jesus Obed Garcia Ruiz | — | (916) 583 4061 | Other | Sacramento · Sacramento County | — | — |
| 3M General Services | Minh Quang Nguyen | — | (408) 472 9395 | HVAC | San Jose · Santa Clara County | — | — |
| 3M Painting Services | Jesus Jorge Molina | — | (310) 430 5046 | Windows, patio, painters | Los Angeles · Los Angeles County | — | — |
| 3M Plumbing INC | Mario Manolo Monterroso Ramirez | — | (818) 800 7524 | Other | Simi Valley · Ventura County | — | — |
| 3M Pools | Mario Mariscal Machaen | — | (909) 630 4300 | Pool | Jurupa Valley · Riverside County | — | — |
| 3M Utilities | 3M Utilities | — | (650) 235 0525 | Other | El Dorado · El Dorado County | — | — |
| 3md Floors | Mauricio Agustin Ayala | — | (831) 444 1488 | Other | Salinas · Monterey County | — | — |
| 3mp Builders INC | Padilla Miguel Perez | — | (408) 314 8810 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| 3P Electric | Christian Carl Peterson | — | (760) 889 0388 | Electricians | San Clemente · Orange County | — | — |
| 3P Landscape | Jose Manuel Cruz | — | (951) 454 2276 | Electricians | Menifee · Riverside County | — | — |
| 3p's Home Improvement INC | Pedro Gabriel Maldonado Santiago | — | (760) 717 6230 | GC, remodel, ADU | Oceanside · San Diego County | — | — |
| 3qc INC | James Mitchell Ogden | — | (916) 496 8400 | GC, remodel, ADU | Folsom · Sacramento County | — | — |
| 3R Construction | Salvador Melchor Medina | info@3r-construction.com | (559) 593 0703 | GC, remodel, ADU | Dinuba · Tulare County | — | — |
| 3R Electric | Bassam Ali Elhambra | — | (714) 768 2787 | Electricians | Riverside · Riverside County | — | — |