| 3G Electric | Camacho Villarreal Gildardo | — | (323) 504 3299 | Electricians | Los Angeles · Los Angeles County | — | — |
| 3G General Construction | Rodriguez Manuel Gonzalez | — | (424) 264 7058 | GC, remodel, ADU | Lancaster · Los Angeles County | — | — |
| 3H Demolition Contracting Services INC | Hector Manuel Alvarado | — | (909) 223 1850 | Other | Whittier · Los Angeles County | — | — |
| 3J Stucco | Franklin Giovanni Ventura | — | (213) 364 7282 | Other | Los Angeles · Los Angeles 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 Painting Services | Jesus Jorge Molina | — | (310) 430 5046 | Windows, patio, painters | Los Angeles · Los Angeles County | — | — |
| 3R Quality Construction | Angelo John Cirrincione | — | (661) 312 6466 | GC, remodel, ADU | Stevenson Ranch · Los Angeles County | — | — |
| 3R Wood Design INC | Nazaryan Romik | — | (818) 388 1515 | GC, remodel, ADU | Pacoima · Los Angeles County | — | — |
| 3rd Dimension Construction | Farnaz Margo Halavy Galdjie | — | (310) 266 6395 | GC, remodel, ADU | Venice · Los Angeles County | — | — |
| 3rd Eye Construction | Pezhman Daroovar | — | (818) 397 8502 | GC, remodel, ADU | West Hills · Los Angeles County | — | — |
| 3rd Generation | 3rd Generation | — | (818) 822 1232 | GC, remodel, ADU | Castaic · Los Angeles County | — | — |
| 3ten Stone & Tile INC | Adam Paul Hammett | — | (805) 298 2254 | Other | West Hills · Los Angeles County | — | — |
| 3wire Refrigeration | Intermediate Holdings Iii LLC Pt | — | (800) 576 0123 | HVAC | Compton · Los Angeles County | — | — |
| 4 Brother's Sheet Metal INC | Isayan Vardan | — | (818) 468 2060 | Other | Glendale · Los Angeles County | — | — |
| 4 C Development | 4 C Development | — | (562) 355 2245 | GC, remodel, ADU | Long Beach · Los Angeles County | — | — |
| 4 Corners Flooring | Khatchig Archie Titizian | — | (818) 612 2575 | GC, remodel, ADU | Granada Hills · Los Angeles County | — | — |
| 4 Kings Construction Site Services | Alberto Zaragoza | — | (323) 559 4945 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 4 Lakes Landscape | Obregon Pedro Valdez | — | (626) 202 3211 | Windows, patio, painters | South El Monte · Los Angeles County | — | — |
| 4 Link Electric | Hany Reyad Metry | — | (310) 210 6524 | Electricians | Santa Clarita · Los Angeles County | — | — |
| 4 N B Construction | Mark Anthony Hernandez | — | (909) 643 6654 | GC, remodel, ADU | Pomona · Los Angeles County | — | — |
| 4 Nu Construction | Larry Marven Grigsby | — | (310) 344 8989 | GC, remodel, ADU | Beverly Hills · Los Angeles County | — | — |
| 4 Over Electric INC | Tarverdians Ara | — | (818) 437 4515 | Electricians | Glendale · Los Angeles County | — | — |
| 4 Season Air | 4 Season Air | — | (818) 482 3277 | HVAC | Sylmar · Los Angeles County | — | — |
| 4 Seasons Builder | Montenegro Nacxil Orozco | — | (323) 802 5054 | GC, remodel, ADU | Long Beach · Los Angeles County | — | — |
| 4 Seasons Concrete INC | Asikati Lata I Muli Satui | — | (916) 370 0985 | Other | Gardena · Los Angeles County | — | — |
| 4 Seasons Construction & Design | Pirayesh Touraj | — | (818) 468 8244 | GC, remodel, ADU | West Hills · Los Angeles County | — | — |
| 4 Seasons HVAC | 4 Seasons HVAC | — | (626) 205 0911 | HVAC | Monrovia · Los Angeles County | — | — |
| 4 Seasons Roofing | Jose Jr Alvarez | — | (818) 810 9987 | Other roofers | North Hills · Los Angeles County | — | — |
| 4 Seasons Roofing INC | Anibal Frias Cabral | — | (323) 726 9615 | Other roofers | Montebello · Los Angeles County | — | — |
| 4 Triplett Construction Corporation | Clarence Ellington | — | (630) 930 2473 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 4 Volt INC | Gharibian Alen | — | (925) 967 4602 | Electricians | Tujunga · Los Angeles County | — | — |
| 4 Waves Management LLC | Tony Michael Blakely | — | (213) 598 9720 | GC, remodel, ADU | Lakeview Terrace · Los Angeles County | — | — |
| 4-by Construction & Plastering INC | Byron Rene Sipaque | — | (310) 345 9396 | GC, remodel, ADU | Gardena · Los Angeles County | — | — |
| 4-eveready Plumbing | 4-eveready Plumbing | — | (562) 477 3187 | Other | Bellflower · Los Angeles County | — | — |
| 4-life Plumbing INC | Nelson E Ceron Cuatro | — | (818) 942 5546 | Other | Panorama City · Los Angeles County | — | — |
| 405 Drywall Co | Hugo Herrera | — | (323) 228 1551 | Other | Bell · Los Angeles County | — | — |
| 413 Builders | 413 Builders | — | (310) 207 1300 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 4214 Fulton Builders INC | Ara Kevork Karajerjian | — | (818) 817 9300 | GC, remodel, ADU | Studio City · Los Angeles County | — | — |
| 43five60 Construction Group INC | Steven Paul Barrera | — | (323) 708 0772 | GC, remodel, ADU | Covina · Los Angeles County | — | — |