| Olayo Landscaping | J Lucas Flores Guadarrama | — | (209) 712 4093 | Windows, patio, painters | Lodi · San Joaquin County | — | — |
| Old World Flooring INC | Larry James Viveiros | — | (209) 462 3734 | Other | Stockton · San Joaquin County | — | — |
| Olivas Construction | Juan Jesus Olivas | — | (509) 930 4329 | GC, remodel, ADU | Vernalis · San Joaquin County | — | — |
| Ollar Flooring | Ollar Flooring | — | (209) 481 8880 | Other | Acampo · San Joaquin County | — | — |
| Olson Construction INC | David Anthony Olson | — | (209) 366 2486 | GC, remodel, ADU | Lodi · San Joaquin County | — | — |
| Olympic Landscaping & Maintenance | Olympic Landscaping & Maintenance | — | (209) 764 0532 | Windows, patio, painters | Escalon · San Joaquin County | — | — |
| Olympus Custom Homes | Olympus Custom Homes | — | (408) 750 4342 | GC, remodel, ADU | Manteca · San Joaquin County | — | — |
| Omega Heater & Air | Perez Angel Coria | — | (209) 817 3198 | HVAC | Stockton · San Joaquin County | — | — |
| Omega Stone Solutions INC | Nick Panagiotis Bozionelos | — | (916) 769 2105 | Other | Lodi · San Joaquin County | — | — |
| Omg Environmental INC | Ronald James Jr Barber | — | (209) 932 0606 | GC, remodel, ADU | Stockton · San Joaquin County | — | — |
| Omstead Electric Construction | Robert Paul Omstead | — | (209) 495 9432 | Electricians | Manteca · San Joaquin County | — | — |
| On Target Construction | Singh Inderjit Bassi | — | (209) 361 8056 | GC, remodel, ADU | Lathrop · San Joaquin County | — | — |
| One Stop Security & Technology INC | Jeffrey David Renison | — | (262) 894 7720 | GC, remodel, ADU | Lodi · San Joaquin County | — | — |
| One Vision Landscape Maintenance LLC | Kevin Anthony Heras | — | (209) 625 6307 | Windows, patio, painters | Victor · San Joaquin County | — | — |
| Onward Welding And Fabrication LLC | Aaron Richard Rolls | — | (661) 623 1665 | Other | Mountain House · San Joaquin County | — | — |
| Optimo Construction INC | Peter Lynn Rodriguez | — | (209) 275 3387 | GC, remodel, ADU | Manteca · San Joaquin County | — | — |
| Optimo Premier Construction INC | Alexa Delfina Paiva | — | (408) 833 0806 | GC, remodel, ADU | Manteca · San Joaquin County | — | — |
| Opus Contracting | Holger Raul Rosero | — | (408) 912 0921 | GC, remodel, ADU | Tracy · San Joaquin County | — | — |
| Ordaz Tapia Construction INC | Olvera Ernesto Ordaz | — | (408) 806 0347 | GC, remodel, ADU | Tracy · San Joaquin County | — | — |
| Orlando Delgadillo | Orlando Delgadillo | — | (209) 603 9034 | GC, remodel, ADU | Escalon · San Joaquin County | — | — |
| Oroson Plumbing | Oroson Plumbing | — | (209) 712 0830 | Other | Lodi · San Joaquin County | — | — |
| Orozco Custom Tile | Orozco Custom Tile | — | (209) 414 0673 | Other | Stockton · San Joaquin County | — | — |
| Ortiz Electric | Victor Manuel Ortiz | — | (209) 279 7538 | Electricians | Stockton · San Joaquin County | — | — |
| Orzala General Contracting | Imtiaz Sabawoon | — | (209) 678 5757 | GC, remodel, ADU | Tracy · San Joaquin County | — | — |
| Oscar Paver | Oscar Paver | — | (925) 428 2337 | Other | Tracy · San Joaquin County | — | — |
| Out Of Sight Fencing INC | Tommy Dale Roy | — | (209) 918 9468 | Other | Tracy · San Joaquin County | — | — |
| Outdoor Landscape Innovations INC | Liliana Yazmin Mendoza Santiago | — | (209) 898 2537 | Windows, patio, painters | Stockton · San Joaquin County | — | — |
| Overhead Door Company Of Stockton INC | William Sherrell Allen | — | (209) 948 2704 | Other | Stockton · San Joaquin County | — | — |
| Overton's Construction | Darren Leshawn Overton | — | (209) 518 4724 | GC, remodel, ADU | Stockton · San Joaquin County | — | — |
| Ozie Electric INC | Oziel Delgado | — | (408) 209 7658 | Electricians | Tracy · San Joaquin County | — | — |
| Ozzborn Security LLC | Robert Glenn Osborne | — | (415) 450-5054 | Alarm and generators | Mountain House · San Joaquin County | — | — |
| P & B Concrete INC | Pedro Oswaldo M Ulloa | — | (209) 640 4685 | Other | Stockton · San Joaquin County | — | — |
| P C M Excavation & Trucking INC | Peter Christian Moller | — | (209) 839 9095 | Other | Tracy · San Joaquin County | — | — |
| P C M S | Jeffrey Gordon Pilgrim | — | (209) 561 8147 | Other | Manteca · San Joaquin County | — | — |
| P M Landscape Construction & Maintenance | Steven Michael Pardo-meiggs | — | (408) 791 4204 | Windows, patio, painters | Tracy · San Joaquin County | — | — |
| P N S B Builders INC | Prashil Nand | — | (510) 304 9398 | GC, remodel, ADU | Stockton · San Joaquin County | — | — |
| P S E Construction | Patrick Saul Easter | — | (209) 271 7608 | GC, remodel, ADU | Stockton · San Joaquin County | — | — |
| Pac- Built INC | Anshuman Sehdev | — | (209) 676 1846 | GC, remodel, ADU | Mountain House · San Joaquin County | — | — |
| Pacas Corporation | Esteban Martin Pacas Martinez | — | (209) 298 8801 | Other | Stockton · San Joaquin County | — | — |
| Pacheco Concrete | Pacheco Concrete | — | (408) 694 8044 | Other | French Camp · San Joaquin County | — | — |