| 1 Day Coatings Ie | 1 Day Coatings Ie | — | (909) 521 2171 | Other | Orange · Orange County | — | — |
| 1 Day Epoxy Flooring | Jay Franklin Goetz | — | (714) 322 3156 | Other | Anaheim · Orange County | — | — |
| 1 Solorio INC | Solorio Alex | — | (714) 578 4709 | GC, remodel, ADU | Orange · Orange County | — | — |
| 1 Superior Electric INC | Rick Daniel Sullivan | info@superior-electric.com | (949) 933 2749 | Electricians | Newport Beach · Orange County | — | — |
| 1 Teamwork Fire Protection | Christopher Alan Cronin | — | (714) 309 2869 | Other | Newport Beach · Orange County | — | — |
| 1 Tom Plumber Anaheim / Brea | Rickie Machie Moore | — | (714) 769 6300 | Other | Anaheim · Orange County | — | — |
| 1-800-coolness | Phillip Robert Paquin | — | (800) 266 5637 | HVAC | Fullerton · Orange County | — | — |
| 100X Construction | Paul Mehrshahi | — | (818) 334 9232 | Electricians | Irvine · Orange County | — | — |
| 10perature Heating And Air Conditioning | Perez Abraham Perez | — | (714) 610 4733 | HVAC | Garden Grove · Orange County | — | — |
| 11B Renewables INC | Otto Ivan Pena | — | (213) 479 5960 | Electricians | Fullerton · Orange County | — | — |
| 1503 Electric INC | Jesus Cirigo Morin | — | (714) 200 9107 | Electricians | Tustin · Orange County | — | — |
| 168cad Construction INC | Gao Peng | — | (626) 777 7757 | GC, remodel, ADU | Yorba Linda · Orange County | — | — |
| 1979 Roofing INC | Juan Carlos Martinez Alvarez | — | (657) 859 0930 | Other roofers | Orange · Orange County | — | — |
| 1st Action Restoration | 1st Action Restoration | — | (855) 379 9257 | GC, remodel, ADU | Mission Viejo · Orange County | — | — |
| 1st Affordable Contractor.com | 1st Affordable Contractor.com | — | (714) 931 1776 | GC, remodel, ADU | Garden Grove · Orange County | — | — |
| 1st Choice Builders Group INC | Richard Roy Hayden | — | (951) 378 5639 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| 1st Choice Construction Solutions | Sean Franklin Dooley | — | (949) 290 9462 | GC, remodel, ADU | Mission Viejo · Orange County | — | — |
| 1st Choice Design & Development | Tony Gene Holder | — | (844) 292 3700 | Electricians | Orange · Orange County | — | — |
| 1st Choice Heating & Air Conditioning INC | Christopher Scott Solar | — | (949) 305 5754 | HVAC | Lake Forest · Orange County | — | — |
| 1st Choice Home Improvement | 1st Choice Home Improvement | — | (714) 288 1888 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| 1st Choice Pool & Spa Solutions | Castillo Ruiz David | — | (949) 355 9396 | Pool | Lake Forest · Orange County | — | — |
| 1st Custom Quality Painting | 1st Custom Quality Painting | — | (714) 329 2042 | Windows, patio, painters | San Juan Capistrano · Orange County | — | — |
| 1st Line Construction | Robert Manuel Delgado | — | (949) 632 0170 | GC, remodel, ADU | Aliso Viejo · Orange County | — | — |
| 1st Place Electric Company INC | Mark Gregory Smith | mark@1stplaceelectric.com | (949) 430-7001 | Electricians | San Juan Capistrano · Orange County | — | — |
| 1st Solution Construction Service | James Joseph Palmeri | — | (888) 988 8337 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| 1st Step Restoration INC | Richard Karl Mccracken | — | (949) 600 8331 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| 1st Street Painting | 1st Street Painting | — | (714) 692 5508 | Windows, patio, painters | Yorba Linda · Orange County | — | — |
| 1st Team All Electrical | Victor Manuel Salazar | — | (323) 346 7908 | Electricians | Anaheim · Orange County | — | — |
| 1st Touch Electric INC | Franklin Andres Martinez Zambrano | fmartinez@1sttouchelectric.com | (714) 865 0430 | Electricians | Anaheim · Orange County | — | — |
| 2 By 4 Construction Company | Chalabi-hajkarim Kasra | — | (714) 791 6381 | GC, remodel, ADU | Mission Viejo · Orange County | — | — |
| 2 Ground Electric | Gabriel Mckinley Fitch | — | (949) 382 6292 | Electricians | Irvine · Orange County | — | — |
| 2 J's Custom Plumbing INC DBA 2 J's Custom Plumbing | Cervantes Hernandez Julio | — | (949) 891 3669 | Other | Anaheim · Orange County | — | — |
| 2 The Point Construction | Walid Louis Makhlouf | — | (714) 305 9894 | GC, remodel, ADU | Yorba Linda · Orange County | — | — |
| 21st Century Air Master H V A C INC | Seyed Fakhridden Alemi | — | (949) 444 8889 | HVAC | Aliso Viejo · Orange County | — | — |
| 22 Builders Co | Luis Reynaldo Pacheco | — | (562) 547 3409 | GC, remodel, ADU | La Habra · Orange County | — | — |
| 24 Hour Bath Enterprises INC | Daniel Guy Liechty | — | (949) 263 0779 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| 24 Hour Restoration & Construction | Bobby Mahmud Ameen | — | (949) 407 6800 | GC, remodel, ADU | Laguna Niguel · Orange County | — | — |
| 24 Security Fire Alarm & Electric | Jea Chun Shin | — | (213) 216 2889 | Electricians | Irvine · Orange County | — | — |
| 24 Seven | 24 Seven | — | (626) 926 6123 | HVAC | Huntington Beach · Orange County | — | — |
| 24/7 Hauling & Demo INC | Jesus Gerardo Munoz | — | (949) 942 7774 | Other | Tustin · Orange County | — | — |