| 1st Class Electric | Javier Percy Alejos | — | (510) 305 8376 | Electricians | San Leandro · Alameda County | — | — |
| 1st Class Fire Safety Compliance | Timothy John Roach | — | (818) 631 8756 | Other | North Hills · Los Angeles County | — | — |
| 1st Class Fireplace & Chimney Inspections INC | Johnny Ray Jr Lankford | — | (661) 310 5131 | Other | Santa Clarita · Los Angeles County | — | — |
| 1st Class Plumbing | 1st Class Plumbing | — | (760) 925 1336 | Other | Escondido · San Diego County | — | — |
| 1st Class Plumbing And Drains LLC | Carlos L Del Toro | — | (510) 220 8523 | Other | Tracy · San Joaquin County | — | — |
| 1st Class Plumbing Repair Service INC | Perez Marcos | — | (909) 804 2476 | Other | San Bernardino · San Bernardino County | — | — |
| 1st Concept Construction INC | Sandeep Amratlal Patel | — | (951) 256 6517 | GC, remodel, ADU | Corona · Riverside County | — | — |
| 1st Custom Quality Painting | 1st Custom Quality Painting | — | (714) 329 2042 | Windows, patio, painters | San Juan Capistrano · Orange County | — | — |
| 1st Demo INC | Juan Manuel Vargas Figueroa | — | (805) 604 7526 | Other | Oxnard · Ventura County | — | — |
| 1st First Prodoor | Jesse Calderon | — | (619) 942 2570 | Other | El Cajon · San Diego County | — | — |
| 1st Gen Floorer | 1st Gen Floorer | — | (323) 667 4219 | Other | Los Angeles · Los Angeles County | — | — |
| 1st Gen HVAC LLC | Fredy Jr Ruiz | — | (510) 375 9084 | HVAC | Richmond · Contra Costa County | — | — |
| 1st Gen Plumbing LLC | Gustavo Arturo Lizarraga | — | (951) 897 3617 | Other | Perris · Riverside County | — | — |
| 1st Home Construction Corp | Ziquan Zhang | — | (626) 620 9751 | GC, remodel, ADU | City Of Industry · Los Angeles County | — | — |
| 1st HVAC INC | Mostafa Mohammad Ashraf | — | (805) 222 6941 | HVAC | Moorpark · Ventura County | — | — |
| 1st Innovative Constructions INC | Keneraki Albert Davidian | — | (818) 497 2344 | GC, remodel, ADU | La Canada · Los Angeles County | — | — |
| 1st Light Sales Corp | Justin Kenneth Krum | — | (209) 456 5415 | Electricians | Manteca · San Joaquin County | — | — |
| 1st Line Construction | Robert Manuel Delgado | — | (949) 632 0170 | GC, remodel, ADU | Aliso Viejo · Orange County | — | — |
| 1st Painting | 1st Painting | sales@1stpainting.com | (805) 707 2204 | Windows, patio, painters | Simi Valley · Ventura County | — | — |
| 1st Place Electric Company INC | Mark Gregory Smith | mark@1stplaceelectric.com | (949) 430-7001 | Electricians | San Juan Capistrano · Orange County | — | — |
| 1st Prime Design Contractors INC | Nejad Hossein Kermani | — | (310) 930 3505 | GC, remodel, ADU | Torrance · Los Angeles County | — | — |
| 1st Response Plumbing & Flood Damage | Robert Damien Cervantes | jared@1stresponseplumbing.com | (858) 203 0930 | HVAC | National City · San Diego County | — | — |
| 1st Rise | Robert S Shamsi | — | (310) 600 3363 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 1st Security & Sound | Robert Tracey Wright | — | (209) 522 6180 | Electricians | Modesto · Stanislaus County | — | — |
| 1st Sign INC | Allen Yu | — | (626) 336 1616 | Other | La Puente · Los Angeles County | — | — |
| 1st Solution Construction Service | James Joseph Palmeri | — | (888) 988 8337 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| 1st Step Flooring | Sanchez Fernando Nolasco | — | (818) 917 0647 | Other | Pacoima · Los Angeles County | — | — |
| 1st Step Restoration INC | Richard Karl Mccracken | — | (949) 600 8331 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| 1st Stop Fencing | 1st Stop Fencing | — | (916) 337 1590 | Other | Shingle Springs · El Dorado County | — | — |
| 1st Streamline Construction INC | Timothy James Stevenson | — | (925) 350 1346 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| 1st Street Painting | 1st Street Painting | — | (714) 692 5508 | Windows, patio, painters | Yorba Linda · Orange County | — | — |
| 1st Team Air Conditioning INC | Brad Webb Daniels | — | (951) 698 7007 | HVAC | Murrieta · Riverside County | — | — |
| 1st Team All Electrical | Victor Manuel Salazar | — | (323) 346 7908 | Electricians | Anaheim · Orange County | — | — |
| 1st Tech Restoration INC | Juana Asuncion Carpio | — | (310) 328 6065 | GC, remodel, ADU | Torrance · Los Angeles County | — | — |
| 1st Touch Electric INC | Franklin Andres Martinez Zambrano | fmartinez@1sttouchelectric.com | (714) 865 0430 | Electricians | Anaheim · Orange County | — | — |
| 1st Watch Technology Solution Incorporated | Shawn Anthony M Dalugdug Kenville | hello@rfuenzalida.com | (833) 302 5276 | Electricians | Chula Vista · San Diego County | — | — |
| 1stopbuilders | Aram Harutyunyan | — | (408) 666 4540 | GC, remodel, ADU | Campbell · Santa Clara County | — | — |
| 1up Drywall | Luis Antonio Garcia | — | (760) 532 6656 | Other | Escondido · San Diego County | — | — |
| 1V Comunications | Jason Leon Wurtz | — | (626) 400 0449 | Other | Jurupa Valley · Riverside County | — | — |
| 1vision Roof Pros | Sergio Duron | — | (619) 289 6378 | Other roofers | San Diego · San Diego County | — | — |