| Assurance Entry Solutions | Assurance Entry Solutions | — | (949) 662 8573 | Other | Costa Mesa · Orange County | — | — |
| Assurant Painting | Assurant Painting | — | (626) 773 0448 | Windows, patio, painters | Irvine · Orange County | — | — |
| Assured Property Maintenance | Assured Property Maintenance | — | (949) 374 6113 | GC, remodel, ADU | Laguna Niguel · Orange County | — | — |
| Assured Roofing Pros INC | Corey Norman Henninger | — | (714) 240 1757 | Other roofers | Huntington Beach · Orange County | — | — |
| Assurepro Water Damage Restoration Corp | Benson Wenceslaus Kane | — | (714) 332 4200 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| Astech Environmental Services INC | Andrew John Schmitt | — | (949) 338 4557 | Other | Mission Viejo · Orange County | — | — |
| Aston C Hill DBA Patchwork's Plastering Company | Aston Cardinal Hill | — | (714) 530 5119 | Other | Garden Grove · Orange County | — | — |
| Astra Builders INC | Dragos Lucian Gavrilescu | — | (714) 404 7057 | Electricians | Anaheim · Orange County | — | — |
| Astro Eclipse INC | James Eric Collins | — | (714) 606 7373 | Other | Placentia · Orange County | — | — |
| Astron Company | Shinali Mir | — | (714) 625 5015 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Asw Construction & Design INC | Alexander Michael Weinberger | — | (909) 276 0165 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| At Home Living Solutions | Barry Lee Lowe | — | (949) 348 0188 | GC, remodel, ADU | Mission Viejo · Orange County | — | — |
| At House | Shigehiro Takanashi | — | (949) 330 0147 | Other | Irvine · Orange County | — | — |
| At Ijk Construction INC | Thomas Tse Ming Liu | — | (714) 808 2273 | GC, remodel, ADU | Orange · Orange County | — | — |
| At1 G Construction And Restorations | Andres Perez | — | (949) 246 5010 | GC, remodel, ADU | Anaheim · Orange County | — | — |
| Atanay Electric Co | Robert Richard Atanay | micah@micahrich.com | (714) 686 8449 | Electricians | La Habra · Orange County | — | — |
| Atg Construction | Ronaldo Rios | — | (714) 658 0660 | GC, remodel, ADU | Orange · Orange County | — | — |
| Atg Developments DBA Atg Poolscapes | Robert Thomas Smith | — | (714) 658 0660 | Pool | Orange · Orange County | — | — |
| Athena Construction Socal INC | Bui Thi Tran | — | (714) 215 2488 | GC, remodel, ADU | Fountain Valley · Orange County | — | — |
| Athome Living Solutions INC | Akar Jay | — | (949) 456 9992 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Athos Construction Co | David Jon Valdez | — | (714) 313 4808 | GC, remodel, ADU | North Tustin · Orange County | — | — |
| Athos Group INC | Lam Dat Quan | — | (714) 713 6311 | Electricians | Cypress · Orange County | — | — |
| Ati | Gary Pierson Moore | — | (714) 283 9990 | Other roofers | Anaheim · Orange County | — | — |
| Ati Restoration Spring Valley Ca INC | Gary Pierson Moore | — | (619) 466 9876 | Other roofers | Anaheim · Orange County | — | — |
| Atl Design Building Services | Michael Nasser Athari | — | (949) 290 3090 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| Atlantic Concrete Cleaning And Restoration | Jose Nelson Lopez | — | (949) 235 7056 | Restoration | Laguna Hills · Orange County | — | — |
| Atlantis Construction Group INC | Johnny Shen | — | (714) 933 0246 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Atlantis Enterprises | Chris Kjell Lemminge | brandon@atlantisenterprises.com | (714) 962 7665 | GC, remodel, ADU | Huntington Beach · Orange County | — | — |
| Atlantis Restoration & Construction Services Co | Ambrosio Jr Acosta | — | (714) 486 1875 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Atlas Cabinets INC | Mohammad Mokhberi | — | (949) 690 7663 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| Atlas Comfort Air | Atlas Comfort Air | — | (714) 402 6972 | HVAC | Garden Grove · Orange County | — | — |
| Atlas Electric Construction | Steve Andrew Clark | — | (949) 650 4835 | Electricians | Huntington Beach · Orange County | — | — |
| Atlas Environmental Engineering INC | Karl Herman Kerner | — | (714) 890 7129 | Other | Huntington Beach · Orange County | — | — |
| Atlas Garage Door Repair INC | Eitan Hugh Franco | — | (714) 844 1751 | Other | Anaheim · Orange County | — | — |
| Atlas Integrated Systems INC | Nickolas Iii Moceri | — | (949) 509 9605 | Other | Irvine · Orange County | — | — |
| Atlas Integration + Security | Joseph Yoo | — | (949) 649 3990 | Alarm and generators | Garden Grove · Orange County | — | — |
| Atlas Marble & Stone Care | Stephen Duane Gillett | — | (714) 953 5353 | Other | Tustin · Orange County | — | — |
| Atlas Pools INC | Tulio Hostilio Jr Alvarez | — | (949) 348 2300 | Windows, patio, painters | Ladera Ranch · Orange County | — | — |
| Atlas Sheet Metal INC | Jon E Pace | — | (949) 600 8787 | Other | Fountain Valley · Orange County | — | — |
| Atlas Structural Retrofit Contractors | Kenneth William Long | — | (714) 731 3600 | GC, remodel, ADU | Tustin · Orange County | — | — |