| Just Plumbing | Just Plumbing | — | (951) 347 2895 | Other | Calimesa · Riverside County | — | — |
| Just Right Air | Timothy Graham Burns | — | (760) 625 8193 | HVAC | Indio · Riverside County | — | — |
| Justice Renovations | Justice Renovations | — | (951) 223 5424 | GC, remodel, ADU | Canyon Lake · Riverside County | — | — |
| Justice Testing | Justice Testing | — | (760) 409 5466 | Other | Cathedral City · Riverside County | — | — |
| Justin D Brians | Justin D Brians | — | (619) 254 2504 | Other | Wildomar · Riverside County | — | — |
| Justin Jones DBA Idyllwild Backhoe | Justin Jones DBA Idyllwild Backhoe | — | (951) 760 2924 | GC, remodel, ADU | Idyllwild · Riverside County | — | — |
| Justin Rexford | Justin Rexford | — | (951) 675 7286 | Tree | Corona · Riverside County | — | — |
| Justin Reynaga Tile Company | Justin Michael Reynaga | — | (951) 823 9939 | Other | Banning · Riverside County | — | — |
| Justin Time Electric | Justin Raymond Lytle | — | (951) 805 4384 | Electricians | Menifee · Riverside County | — | — |
| Justin V Frankian | Justin V Frankian | — | (818) 970 3123 | GC, remodel, ADU | Coachella · Riverside County | — | — |
| Justus Concrete Solutions | Justus Concrete Solutions | — | (951) 239 2594 | Other | Riverside · Riverside County | — | — |
| Justus Fence INC | John Mark Justus | — | (951) 699 1563 | Other | Temecula · Riverside County | — | — |
| Jv Caulking INC | Juan Santos Vanegas | — | (703) 539 9612 | GC, remodel, ADU | Hemet · Riverside County | — | — |
| Jv Masonry & Concrete INC | Juan Carlos Valdez Becerra | — | (760) 548 8227 | Other | Thermal · Riverside County | — | — |
| Jv Quality Painting Corp | Jasmine Del Rosario Veliz Cruz | — | (951) 756 1836 | Windows, patio, painters | Jurupa Valley · Riverside County | — | — |
| Jvc Construction | Juan Carlos Villavicencio | — | (310) 208 9317 | GC, remodel, ADU | Temecula · Riverside County | — | — |
| Jvr Asphalt Contractor | Jvr Asphalt Contractor | — | (951) 470 4051 | Other | Riverside · Riverside County | — | — |
| Jvr Landscape | Luis Angel Rizo Gomez | — | (951) 579 0812 | Windows, patio, painters | Lake Elsinore · Riverside County | — | — |
| Jw Engineering INC | Jeffrey Jay Williams | — | (951) 216 5466 | Other | Murrieta · Riverside County | — | — |
| Jwj Construction Services INC | Darrick Tramont Sr Jordan | — | (855) 653 2687 | GC, remodel, ADU | Temecula · Riverside County | — | — |
| Jyj Air Conditioning INC | Juan Manuel Salinas Perez | — | (626) 340 5484 | HVAC | Riverside · Riverside County | — | — |
| Jz Creative Concrete Related Services & Designs | Zetina Cardozo Jose | — | (760) 980 5545 | Other | Desert Hot Springs · Riverside County | — | — |
| Jz Renovations INC | Jesse Alejandro Zazueta | jzazuetarenovations@gmail.com | (760) 574 4678 | GC, remodel, ADU | Coachella · Riverside County | — | — |
| Jzs Master Heating & Cooling Services | Song Junzhan | — | (626) 428 5788 | HVAC | Riverside · Riverside County | — | — |
| K & L Professional Painting | Kenneth William Jones | — | (951) 681 7401 | Windows, patio, painters | Riverside · Riverside County | — | — |
| K & L Roofing INC | Luis C Gonzalez Solano | — | (951) 415 4579 | Other roofers | Riverside · Riverside County | — | — |
| K & P Company | Sakshi Gopal Saxena | — | (714) 231 2872 | Electricians | Winchester · Riverside County | — | — |
| K & V Construction | Kristian Andrew Lundvall | — | (951) 836 1924 | GC, remodel, ADU | Riverside · Riverside County | — | — |
| K 2 Fabrication INC | David Eugene King | — | (714) 231 8930 | GC, remodel, ADU | Norco · Riverside County | — | — |
| K A Eredia Construction | Keith Alan Eredia | — | (714) 501 4556 | GC, remodel, ADU | Lake Elsinore · Riverside County | — | — |
| K A General Construction | Mario Antonio Razo Lara | — | (760) 574 9134 | GC, remodel, ADU | Desert Hot Springs · Riverside County | — | — |
| K A L Cabinets | K A L Cabinets | — | (951) 836 0679 | Other | Nuevo · Riverside County | — | — |
| K And F Builders INC | Freddy Emmanuel Ruiz | — | (951) 312 5619 | GC, remodel, ADU | Perris · Riverside County | — | — |
| K B C Coatings | K B C Coatings | — | (951) 678 8114 | Windows, patio, painters | Lake Elsinore · Riverside County | — | — |
| K B P Electric | Keith Brendan Proctor | — | (951) 795 6474 | Electricians | Temecula · Riverside County | — | — |
| K B Plastering | K B Plastering | — | (714) 235 5916 | Other | Canyon Lake · Riverside County | — | — |
| K Belle Kreations LLC | Kelly Marie Barttels | — | (951) 519 1643 | GC, remodel, ADU | Temecula · Riverside County | — | — |
| K C Plumbing INC | Kenneth David Cantrell | — | (408) 507 2219 | Other | Temecula · Riverside County | — | — |
| K C R Contracting Services | Richard John Galippo | — | (951) 232 0414 | Windows, patio, painters | Corona · Riverside County | — | — |
| K D I Elements | Paul Vincent Klein | — | (760) 345 9933 | Other | Palm Desert · Riverside County | — | — |