| 4 Granite INC | Joe Webb | — | (760) 403 3376 | GC, remodel, ADU | Apple Valley · San Bernardino County | — | — |
| 4 J Drywall Corp | Retana Hugo Sanchez | — | (909) 539 8108 | GC, remodel, ADU | Fontana · San Bernardino County | — | — |
| 4 Points A/c And Heating | Abelar Lopez Martin | — | (909) 280 3318 | HVAC | San Bernardino · San Bernardino County | — | — |
| 4 S Air INC | Spencer Loster | — | (909) 576 6586 | HVAC | Rancho Cucamonga · San Bernardino County | — | — |
| 4 X 4 Studio | 4 X 4 Studio | csy@systempia.com | (909) 214 9459 | Electricians | Chino · San Bernardino County | — | — |
| 4D Milling INC | Chandler Joseph Anglin | — | (909) 709 7757 | Other | Oak Glen · San Bernardino County | — | — |
| 4D Surface Management INC | Michael Chris Doucette | — | (909) 797 0419 | Other | Yucaipa · San Bernardino County | — | — |
| 4ever Painting | 4ever Painting | — | (909) 346 5224 | Windows, patio, painters | Rancho Cucamonga · San Bernardino County | — | — |
| 4je Plumbing | 4je Plumbing | — | (909) 638 9446 | Other | Fontana · San Bernardino County | — | — |
| 4S Epoxy & Polish Concrete INC | Silvia Sanchez | — | (909) 270 6970 | Other | Ontario · San Bernardino County | — | — |
| 5 Brother's Painting & General Construction INC | Rafael Perez | — | (909) 648 0408 | GC, remodel, ADU | San Bernardino · San Bernardino County | — | — |
| 5 Star Construction And Remodeling INC | Juan Francisco Sanchez Campos | — | (562) 833 4088 | GC, remodel, ADU | San Bernardino · San Bernardino County | — | — |
| 5 Star Plumbing LLC | Fernando Jr Sanchez | — | (909) 841 1057 | Other | Colton · San Bernardino County | — | — |
| 5 Stars Plumbing & Sewer | 5 Stars Plumbing & Sewer | — | (510) 220 8859 | Other | Bloomington · San Bernardino County | — | — |
| 626 Plumbing INC | Lu Paul | — | (626) 650 3003 | GC, remodel, ADU | Chino Hills · San Bernardino County | — | — |
| 81 Construction INC | Moises Ivan Acosta Garcia | — | (310) 409 9549 | GC, remodel, ADU | Rialto · San Bernardino County | — | — |
| 811 Plumbing | 811 Plumbing | — | (951) 481 8080 | Other | Rialto · San Bernardino County | — | — |
| 848 Designs INC | Daniel Ramon Gurule-Avendano | — | (909) 520 5195 | Other | Rialto · San Bernardino County | — | — |
| 86 Design & Build | 86 Design & Build | — | (626) 757 5139 | GC, remodel, ADU | Fontana · San Bernardino County | — | — |
| 8A Construction Services INC | Ivan Ochoa Moreno | — | (323) 896 3570 | GC, remodel, ADU | Ontario · San Bernardino County | — | — |
| 90 Degree Construction | Gregory Carrillo Ramos | — | (909) 747 7556 | GC, remodel, ADU | Redlands · San Bernardino County | — | — |
| 91 Volts | 91 Volts | — | (951) 232 7029 | Other | Alta Loma · San Bernardino County | — | — |
| 911 Plumbing INC | Omar Luna-Flores | — | (951) 970 8928 | GC, remodel, ADU | Colton · San Bernardino County | — | — |
| 9500 Engineering Construction | Gregory Alan Gates | — | (909) 627 0200 | Other | Chino · San Bernardino County | — | — |
| A & A Builders Group INC | Agustin Mendoza | — | (626) 488 2740 | GC, remodel, ADU | Fontana · San Bernardino County | — | — |
| A & A General Contracting Company | Acevedo Alejandro | — | (909) 685 5363 | HVAC | Colton · San Bernardino County | — | — |
| A & B General Construction Services | Campos Armando Barrales | armando@abgeneralconstructionservices.com | (626) 252 5785 | GC, remodel, ADU | Rialto · San Bernardino County | — | — |
| A & B Window Treatment Incorporated | Barbaro N Basulto Acosta | — | (909) 561 5453 | Other | Fontana · San Bernardino County | — | — |
| A & C Construction | Paul Alan Argetsinger | — | (760) 910 4202 | GC, remodel, ADU | Yucca Valley · San Bernardino County | — | — |
| A & C Electric INC | Michael Scott Christiansen | — | (626) 786 1754 | Electricians | Rancho Cucamonga · San Bernardino County | — | — |
| A & C Professional Plumbing Corp | Fabiola Cortez | — | (909) 278 2166 | Other | Rialto · San Bernardino County | — | — |
| A & G Air Conditioning Services | Lopez Adrian | — | (909) 350 3737 | HVAC | Fontana · San Bernardino County | — | — |
| A & J Plumbing Company | Art Cortez | — | (877) 267 7567 | Other | Colton · San Bernardino County | — | — |
| A & J Scaffold INC | Noemi Villagomez | levi@ajscaffold.com | (909) 214 4323 | Other | Fontana · San Bernardino County | — | — |
| A & L Plastering | A & L Plastering | — | (909) 827 7400 | Other | Fontana · San Bernardino County | — | — |
| A & M Contractors | Catinean Marcel | — | (909) 731 2535 | Other roofers | Redlands · San Bernardino County | — | — |
| A & M Electrical Construction INC DBA A & M Construction | Alecsandru Catinean | — | (909) 674 6364 | Electricians | Redlands · San Bernardino County | — | — |
| A & O Construction & Design INC | Kc Hahn | — | (323) 482 4262 | GC, remodel, ADU | Pinon Hills · San Bernardino County | — | — |
| A & R Concrete & Hardscape | Richard John Harvey | richard@arconcretehardscape.com | (909) 908 5561 | Other | Rancho Cucamonga · San Bernardino County | — | — |
| A & R Concrete Construction | Denis Samuel Zepeda | — | (909) 800 1657 | Other | Rancho Cucamonga · San Bernardino County | — | — |