| One Choice Pool & Spa Service | Loza Tony Gutierrez | — | (916) 276 0347 | Pool | Rocklin · Placer County | — | — |
| One Day Sacramento | Dairl M Johnson | — | (916) 840 2057 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| One Hit Wonder Woodworking And Handyman | Jonathan Edward Wais | — | (916) 626 7370 | Other | Colfax · Placer County | — | — |
| One Nest Property Management | One Nest Property Management | — | (916) 259-3467 | Property managers | Lincoln · Placer County | — | — |
| One Off Wood Designs INC | Bruce Roger Wallace | — | (916) 622 0294 | Other | Colfax · Placer County | — | — |
| One Source Mobility INC | Stefan Alexander Iii Grzebski | info@onesourcemobility.com | (530) 518 3294 | GC, remodel, ADU | Roseville · Placer County | — | — |
| One Up Construction | Richard John Von Alvensleben | — | (916) 439 3180 | GC, remodel, ADU | Loomis · Placer County | — | — |
| Onsite Welding Company LLC | Benjamin Charles Krause | — | (916) 295 8990 | Other | Lincoln · Placer County | — | — |
| Oppainting Net INC | Andrey Panasyuk | — | (916) 384 8892 | Windows, patio, painters | Granite Bay · Placer County | — | — |
| Optima Co Of California INC | Hernandez Pedro Sandoval | — | (916) 865 7522 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Optima Landscape Of Sacramento INC | Blanca Estela Mendoza | — | (916) 799 9500 | Windows, patio, painters | Roseville · Placer County | — | — |
| Opw Flooring | Opw Flooring | — | (916) 871 8357 | Other | Rocklin · Placer County | — | — |
| Orco's Flooring | Orco's Flooring | — | (916) 501 3244 | Other | Roseville · Placer County | — | — |
| Origin Solar Usa INC | Bernard William Lewis | info@originsolarusa.com | (844) 878 7828 | Other roofers | Roseville · Placer County | — | — |
| Orion Custom Woodworking | Orion Custom Woodworking | — | (916) 247 4803 | GC, remodel, ADU | Lincoln · Placer County | — | — |
| Orlando Enterprises Tahoe INC | Lawrence Joseph Orlando | — | (530) 546 5567 | GC, remodel, ADU | Carnelian Bay · Placer County | — | — |
| Ortega Landscape INC | Elmer Donai Ortega Robles | — | (916) 640 7916 | Windows, patio, painters | Roseville · Placer County | — | — |
| Orz Construction | Oleg Yevgenyevich Reznichenko | orzconstructionllc@yahoo.com | (916) 212 5204 | GC, remodel, ADU | Newcastle · Placer County | — | — |
| Osborn Construction | Steven Currier Osborn | — | (530) 510 7600 | GC, remodel, ADU | Tahoe City · Placer County | — | — |
| Osborn Rock Walls | Baisha Osborn Lee Claxton | — | (530) 878 2106 | Other | Meadow Vista · Placer County | — | — |
| Osborne Construction Co | Marc Everett Osborne | — | (916) 878 9973 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Osella Construction LLC | Joseph Albert Osella | — | (916) 956 0228 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Oswald General Contracting | David Charles Oswald | — | (916) 847 3246 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| Ot Construction | Cristian Petruescu | — | (916) 626 2989 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| Out Of Sight Screens | Out Of Sight Screens | — | (530) 492 0112 | Other | Colfax · Placer County | — | — |
| Out On A Limb | Out On A Limb | — | (530) 906 8733 | GC, remodel, ADU | Colfax · Placer County | — | — |
| Out On A Limb | Out On A Limb | — | (530) 263 3476 | Tree | Foresthill · Placer County | — | — |
| Outdoor Services INC | Ryan Mark Grimes | — | (916) 316 3211 | Pool | Loomis · Placer County | — | — |
| Outer-spaces Landscape Construction | David Wayne Calhoun | — | (916) 432 9222 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Outerbridge Electrical Contractors | Mike Karel Outerbridge | — | (916) 660 1753 | Electricians | Loomis · Placer County | — | — |
| Owens Const | Owens Const | — | (530) 878 3905 | GC, remodel, ADU | Applegate · Placer County | — | — |
| Oznell Builders | Oznell Builders | — | (916) 214 0271 | GC, remodel, ADU | Roseville · Placer County | — | — |
| P E G Construction INC | Paul Marvin Jr Morlas | — | (916) 417 7155 | Electricians | Rocklin · Placer County | — | — |
| P G A Custom Remodeling INC | Pavel A Gerbel | pgacustomremodeling@gmail.com | (916) 595 3694 | GC, remodel, ADU | Newcastle · Placer County | — | — |
| P K Construction | Paul Martin Kelly | — | (916) 698 7555 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| P K Flooring | P K Flooring | — | (530) 546 5582 | Other | Carnelian Bay · Placer County | — | — |
| P M Construction LLC | Carter Sterling Pierce | — | (530) 235 6630 | HVAC | Auburn · Placer County | — | — |
| P N P Construction INC | Shawn Eric Payne | — | (530) 885 9360 | GC, remodel, ADU | Applegate · Placer County | — | — |
| P T L Pool Service & Repair | Clifford Malcolm Nelson | — | (916) 782 5674 | Pool | Roseville · Placer County | — | — |
| P6 Commercial Maintenance | Steven David Mays | — | (916) 414 0444 | GC, remodel, ADU | Newcastle · Placer County | — | — |