| Building Maintenance Unit Services | Zereh Nazi Ali | — | (949) 648 4820 | Other | Mission Viejo · Orange County | — | — |
| Building Resource Service | Steven D Taylor | — | (949) 235 2754 | HVAC | Tustin · Orange County | — | — |
| Building Specs Home Inspection Service | Building Specs Home Inspection Service | — | (888) 773-2711 | Inspectors | Dana Point · Orange County | — | — |
| Building Worx INC | Robert Edward Artura | — | (626) 385 6582 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Buildliner INC | Morteza K Panbechi | info@buildliner.com | (949) 743 4415 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Buildlion | Juan Carlos Murillo | — | (714) 474 8521 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Buildly Design & Construction INC | Matthew David Blake | — | (949) 207 3353 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Buildnetx Consultants INC | Mahmoud Baei | — | (949) 228 8508 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Buildov LLC | Aleksei Shcherbakov | — | (424) 521 3626 | GC, remodel, ADU | Westminster · Orange County | — | — |
| Buildpro | Matthew William Barry | — | (949) 257 5911 | GC, remodel, ADU | San Juan Capistrano · Orange County | — | — |
| Buildpro Carpet One Floor & Home | Kevin Patrick Barry | — | (714) 308 0694 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Buildquest INC | George Clifford Iii Baker | — | (949) 933 2411 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Buildrite INC | Louis David Jaquin | — | (714) 547 7737 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Buildswell Development | Buildswell Development | — | (562) 824 8775 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Buildup Construction | Darcy Lyle Gionfriddo | — | (561) 271 8743 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| Buildwatt INC | Alireza Zandnick | — | (714) 714 0197 | Electricians | Irvine · Orange County | — | — |
| Buildwave Construction INC | Stephanie Pham | — | (714) 360 7510 | GC, remodel, ADU | Garden Grove · Orange County | — | — |
| Buildwell Construction | Troy Marron Franckowiak | — | (310) 350 8224 | GC, remodel, ADU | Laguna Niguel · Orange County | — | — |
| Buildwise Builders | Christopher James Antoszek | — | (714) 493 9736 | Electricians | Irvine · Orange County | — | — |
| Buildwise Spaces LLC | Chen Bowen | — | (949) 518 6622 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Builpire INC | Dean Namin | m.bahramibb12@gmail.com | (818) 927 1444 | Other roofers | Santa Ana · Orange County | — | — |
| Built By Beast INC | Salvador James Aguilera | — | (323) 558 3769 | GC, remodel, ADU | Brea · Orange County | — | — |
| Built By Matt A Mobile Home Contractor | Matthew James Roberts | — | (714) 580 2266 | Other | Huntington Beach · Orange County | — | — |
| Built By Newkirk Ltd | Brian Victor Newkirk | — | (714) 525 6559 | GC, remodel, ADU | Fullerton · Orange County | — | — |
| Built On The Rock Construction | Jonathan Curtis Cefalia | — | (949) 677 6697 | GC, remodel, ADU | Costa Mesa · Orange County | — | — |
| Built To Last | Built To Last | — | (949) 498 3731 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Built Xd LLC | David Quoc Nguyen | — | (949) 522 5235 | GC, remodel, ADU | Santa Ana · Orange County | — | — |
| Builteck Co | Abrahim Etemad-Haary | info@builteck.com | (949) 943 0751 | Electricians | Irvine · Orange County | — | — |
| Builtpro Painting And Construction | Timothy Robert Meyer | — | (949) 392 0611 | GC, remodel, ADU | Lake Forest · Orange County | — | — |
| Builtwell Design Build Co | Darren Lee Roys | — | (949) 466 9695 | GC, remodel, ADU | Irvine · Orange County | — | — |
| Bulldog Construction & Development INC | James Paterson Iii Kennedy | — | (949) 922 0929 | GC, remodel, ADU | San Clemente · Orange County | — | — |
| Bullet Refinishing Coatings INC | Edgardo Lozada | — | (714) 204 6605 | Other | Orange · Orange County | — | — |
| Bullseye Construction Corp | Amendola Austin Roski | — | (818) 519 7959 | GC, remodel, ADU | Newport Beach · Orange County | — | — |
| Bultsma Innovations LP | Lori Lynette Bultsma | — | (714) 588 2887 | Other | Orange · Orange County | — | — |
| Bunny Painting Maintenance | Bunny Painting Maintenance | — | (714) 478 9799 | Windows, patio, painters | Garden Grove · Orange County | — | — |
| Bup Nguyen Construction | Nguyen Bup Construciton | — | (714) 425 8715 | GC, remodel, ADU | Westminster · Orange County | — | — |
| Buratti Construction INC | Paul Albert Buratti | — | (949) 697 5759 | GC, remodel, ADU | Laguna Hills · Orange County | — | — |
| Burch & Co Millworks | Brian Darrell Burch | — | (714) 343 4036 | Other | Orange · Orange County | — | — |
| Burch Construction Management | David Michael Burch | — | (714) 864 0356 | GC, remodel, ADU | Brea · Orange County | — | — |
| Burdett Glass INC | Kathy Rita Burdett | — | (714) 928 2022 | Windows, patio, painters | Brea · Orange County | — | — |