| Orchard's Tree Service INC | Omar Ricardo Lopez Noriega | adolfo@orchardstreeservice.com | (650) 435 2402 | GC, remodel, ADU | Los Gatos · Santa Clara County | — | — |
| Orion Electric | Gholam Hossein Zardkoohi | interested@domainmarket.com | (408) 887 2767 | Electricians | San Jose · Santa Clara County | — | — |
| Ornelas Heating & Air Conditioning | Ornelas Heating & Air Conditioning | — | (408) 813 6020 | HVAC | San Jose · Santa Clara County | — | — |
| Ornelas Landscaping INC | Jovanni Avalos | — | (408) 510 8096 | Windows, patio, painters | Gilroy · Santa Clara County | — | — |
| Orona Landscaping | Orona Landscaping | amkryukov@gmail.com | (408) 202 3462 | Windows, patio, painters | Morgan Hill · Santa Clara County | — | — |
| Orozco Construction INC | Godinez Leopoldo Orozco | — | (408) 472 2839 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Orozco Landscapes INC | Servin Federico Orozco | — | (408) 569 4718 | Windows, patio, painters | Sunnyvale · Santa Clara County | — | — |
| Orozco Plumbing & Rooter | Orozco Plumbing & Rooter | — | (408) 507 0227 | Other | Santa Clara · Santa Clara County | — | — |
| Orozco Prolandscape INC | Orozco Jose Diaz | — | (408) 702 8818 | Windows, patio, painters | Sunnyvale · Santa Clara County | — | — |
| Orsua Framing Company | Richard George Orsua | — | (209) 778 0028 | Other | San Jose · Santa Clara County | — | — |
| Ortega Core Drilling Concrete Cutting | Ortega Core Drilling Concrete Cutting | ortegacoredrilling@yahoo.com | (408) 209 3993 | Other | San Jose · Santa Clara County | — | — |
| Ortiz Anduaga Construction INC | Diana Joselin Anduaga | — | (408) 623 4923 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Ortiz Construction | Ortiz Ruben | interested@domainmarket.com | (408) 610 0900 | GC, remodel, ADU | Gilroy · Santa Clara County | — | — |
| Oscar Aguilar | Oscar Aguilar | contacto@oscaraguilar.com | (408) 726 4536 | Other | San Jose · Santa Clara County | — | — |
| Oscar Arguello | Oscar Arguello | — | (408) 767 6030 | HVAC | Morgan Hill · Santa Clara County | — | — |
| Oscar Builders INC | Gilbert Rivera | contact@oscarbuilders.com | (408) 836 2702 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Oscar's Expert Tree Service INC | Oscar Urvizo Tellez | info@oscarsexperttreeservice.com | (408) 373 4696 | Tree | San Jose · Santa Clara County | — | — |
| Osea Iron Works | Osea Iron Works | — | (669) 270 9446 | Other | Morgan Hill · Santa Clara County | — | — |
| Oss HVAC INC | Alberto Antonio Duran | aduran@oss-hvac.com | (408) 607 7799 | HVAC | Gilroy · Santa Clara County | — | — |
| Osuna Excavation Services | Jesse James Osuna | — | (408) 726 2194 | Other | Morgan Hill · Santa Clara County | — | — |
| Oswalt Developers | Oswalt Developers | — | (408) 313 7000 | Other | Los Gatos · Santa Clara County | — | — |
| Ot Bay Builders INC | James Richard Grode | office@otbaybuilders.com | (408) 766 7272 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Ota Construction INC | Oscar Francisco Torres | — | (408) 249 9233 | GC, remodel, ADU | Santa Clara · Santa Clara County | — | — |
| Otovo Builders | Otovo Builders | — | (408) 480 0802 | GC, remodel, ADU | Los Gatos · Santa Clara County | — | — |
| Otte Construction INC | Michael Edward Otte | — | (408) 656 7888 | GC, remodel, ADU | Santa Clara · Santa Clara County | — | — |
| Out Door Solutions | Out Door Solutions | — | (650) 776 9675 | Other | Palo Alto · Santa Clara County | — | — |
| Outermost Metal Panels | Nikolay Viktorovich Mishakov | — | (917) 215 8422 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Outertainment Construction INC | Audrianna Correa-Jimenez | — | (408) 960 8369 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Outscape Concrete & Landscape INC | Torres-madrigal Argel | — | (408) 658 2851 | Windows, patio, painters | Gilroy · Santa Clara County | — | — |
| Ova Electric LLC | Eduardo Alberto Guzman | — | (669) 294 5828 | Electricians | San Jose · Santa Clara County | — | — |
| Oveisi Construction INC | Oveisi Babak | — | (650) 276 8910 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Overlook Networks | Paul Joseph Nolan | info@overlooknetworks.com | (408) 884 4095 | Other | Los Gatos · Santa Clara County | — | — |
| Owen Plumbing | Owen Plumbing | — | (408) 984 6936 | Other | San Jose · Santa Clara County | — | — |
| Owen Plumbing And General Contracting INC | Richard Wayne Olivo | — | (408) 984 6936 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| Owner's Logic INC | Kevin Chiao | — | (408) 472 4127 | GC, remodel, ADU | Mountain View · Santa Clara County | — | — |
| Ozone Service DBA Ozone HVAC | Alexander Dorofeev | — | (310) 743 3364 | HVAC | San Jose · Santa Clara County | — | — |
| Ozzy Construction INC | Micaela G Naranjo | — | (408) 717 3229 | Electricians | San Jose · Santa Clara County | — | — |
| P & T General Construction Company INC | Toula Stouras | — | (408) 224 4655 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| P And L Sheetmetal | Luz-Maria Romo Martin | — | (408) 859 3947 | HVAC | San Jose · Santa Clara County | — | — |
| P C Building And Construction | Pedro Campos | — | (408) 963 1513 | GC, remodel, ADU | Morgan Hill · Santa Clara County | — | — |