| Nsod Jv | Star Government Services North | — | (916) 251 5500 | Other | Roseville · Placer County | — | — |
| Nu Visions Construction Company | James Michael Halajian | — | (530) 416 2281 | GC, remodel, ADU | Tahoma · Placer County | — | — |
| Nusom Custom Builders INC | Andrew Michael Hammond | — | (916) 871 9271 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| O Tile LLC | Isaac John Ostrom | — | (916) 259 2840 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| O'connor And Duke Sole Owner | O'connor And Duke Sole Owner | — | (530) 889 8090 | GC, remodel, ADU | Auburn · Placer County | — | — |
| O'connor Electric | George Joseph O'connor | oconnorelectric@comcast.net | (916) 772 4776 | Electricians | Granite Bay · Placer County | — | — |
| O'connor Pool Solutions INC | Kevin James O'connor | — | (916) 871 5097 | Pool | Roseville · Placer County | — | — |
| O'leary Custom Building INC | Timothy Sean O'leary | — | (530) 583 1304 | GC, remodel, ADU | Carnelian Bay · Placer County | — | — |
| Oak Lake Builders INC | Mark David Straks | — | (530) 830 0044 | GC, remodel, ADU | Meadow Vista · Placer County | — | — |
| Oak Valley Fence LLC | Eric Martinez | — | (916) 295 2803 | Other | Auburn · Placer County | — | — |
| Oakcreek Construction INC | Junjie Li | — | (626) 715 0988 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| Oakhills Painting | Oakhills Painting | — | (916) 496 0343 | Windows, patio, painters | Granite Bay · Placer County | — | — |
| Oaks Construction | Donald Neal Jr Allen | — | (916) 289 5444 | GC, remodel, ADU | Loomis · Placer County | — | — |
| Oakwood Remodeling Group | Ion Tincu | — | (916) 907 8782 | GC, remodel, ADU | Lincoln · Placer County | — | — |
| Obie Maurer General Builder | Obie Maurer General Builder | — | (916) 709 2537 | GC, remodel, ADU | Newcastle · Placer County | — | — |
| Odehnal Electric | Robert Francis Odehnal | — | (916) 223 9921 | Electricians | Roseville · Placer County | — | — |
| Odin | Louay Malek Owaidat | — | (916) 251 5501 | Other | Roseville · Placer County | — | — |
| Odin - Raito Jv | INC Raito | — | (916) 251 5500 | Other | Roseville · Placer County | — | — |
| Odin Real Estate Group LLC | Louay Malek Owaidat | — | (916) 251 5500 | Other | Loomis · Placer County | — | — |
| Ojeda & Son Concrete INC | Edward Rivera Ojeda | — | (916) 529 3698 | Other | Auburn · Placer County | — | — |
| Ojeda Landscaping Design | Ojeda Landscaping Design | — | (916) 298 6977 | Windows, patio, painters | Roseville · Placer County | — | — |
| Oktavian Karp | Oktavian Karp | — | (916) 743 3455 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Old Oak Construction | Stephen Michael Olson | — | (916) 825 6233 | GC, remodel, ADU | Newcastle · Placer County | — | — |
| Olenders Excavating INC | Jonathan Michael Olender | — | (530) 906 7623 | Other | Weimar · Placer County | — | — |
| Olive Homes INC | Elvira Sacara Chernyavskiy | info@olivehomes.com | (916) 384 8510 | GC, remodel, ADU | Auburn · Placer County | — | — |
| Olive Tech Solution | Olive Tech Solution | — | (916) 879 9293 | Electricians | Loomis · Placer County | — | — |
| Oliver Douglas | Oliver Douglas | sales@newsmiths.co.uk | (530) 368 1898 | GC, remodel, ADU | Gold Run · Placer County | — | — |
| Oltex Corporation | Terletskiy Oleg | — | (916) 224 6555 | GC, remodel, ADU | Auburn · Placer County | — | — |
| Olympus Electric | Jared Nalani Ezell | — | (916) 752 3074 | Electricians | Roseville · Placer County | — | — |
| Olympus Pointe Landscape INC | Kevin Roderick Massey | — | (916) 782 5296 | Windows, patio, painters | Roseville · Placer County | — | — |
| Omarion | Omar Mohamed Ali Alaffas | — | (916) 218 5517 | Electricians | Granite Bay · Placer County | — | — |
| Omega Floors | Omega Floors | — | (916) 804 3322 | GC, remodel, ADU | Rocklin · Placer County | — | — |
| Omega Landscaping & Construction INC | Ranjit Singh | — | (916) 765 7562 | GC, remodel, ADU | Roseville · Placer County | — | — |
| Omni Structures & Management INC | Roderick Kenneth Thayer | — | (916) 787 1121 | GC, remodel, ADU | Roseville · Placer County | — | — |
| On - Site Engineering And Asphalt | Kenneth Allen Pinkham | — | (916) 652 0600 | Other | Loomis · Placer County | — | — |
| On The House Painting | On The House Painting | — | (916) 297 1215 | Windows, patio, painters | Lincoln · Placer County | — | — |
| On The Level Construction | Kenneth Richard Hamilton | — | (916) 548 6958 | GC, remodel, ADU | Granite Bay · Placer County | — | — |
| On The Ritz Plumbing INC | Brek John Ritzema | — | (916) 770 0624 | Other | Penryn · Placer County | — | — |
| On Time Landscaping Services | Jose Luis Torres Guzman | — | (530) 368 9839 | Windows, patio, painters | Auburn · Placer County | — | — |
| On-site Engineering & Asphalt | Kenneth Allen Pinkham | — | (916) 652 0600 | Other | Loomis · Placer County | — | — |