| Galan Construction INC | Harry M Galan | galanconstruction@sbcglobal.net | (650) 222 7636 | GC, remodel, ADU | Walnut Creek · Contra Costa County | — | — |
| Galaxy Construction Services INC | Knop Alex | — | (415) 756 0950 | HVAC | Pleasant Hill · Contra Costa County | — | — |
| Galaxy Heating & Air Conditioning | Ron Borisov | — | (925) 233 7378 | HVAC | Pleasant Hill · Contra Costa County | — | — |
| Galicia Hardwood Floors | Galicia Hardwood Floors | — | (925) 813 2521 | Other | Martinez · Contra Costa County | — | — |
| Galindo Tree Care INC | Ortiz Jonathan Procopio | galindotreeservices@gmail.com | (925) 289 6144 | Tree | Concord · Contra Costa County | — | — |
| Gallardo Landscape Design | Gallardo Landscape Design | — | (415) 686 7844 | Windows, patio, painters | Pinole · Contra Costa County | — | — |
| Gallardo Landscaping | Gallardo Landscaping | — | (925) 997 4055 | Windows, patio, painters | Brentwood · Contra Costa County | — | — |
| Galletti Concrete | Galletti Concrete | — | (925) 826 4312 | Other | Concord · Contra Costa County | — | — |
| Gallino Landscaping | Gallino Landscaping | — | (510) 222 9273 | Windows, patio, painters | El Sobrante · Contra Costa County | — | — |
| Gallwitz Homes | Gallwitz Homes | — | (925) 354 0438 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Galu Engineering | Galu Engineering | — | (510) 478 2417 | Other | San Pablo · Contra Costa County | — | — |
| Gamble's Flooring INC | Daniel Frederick Gamble | proteam@mopro.com | (925) 933 9999 | Other | Pleasant Hill · Contra Costa County | — | — |
| Gandaras Construction Company INC | Carlos Adrian Gandara | — | (925) 436 6132 | Electricians | Antioch · Contra Costa County | — | — |
| Gant Construction | Thomas Rodney Gant | — | (925) 386 0547 | GC, remodel, ADU | Orinda · Contra Costa County | — | — |
| Gao Chao Construction Company | Guo Zhaojun | — | (510) 965 7555 | GC, remodel, ADU | San Ramon · Contra Costa County | — | — |
| Gap Electric | Gonzalo Elias Amador | — | (510) 253 4045 | Electricians | Concord · Contra Costa County | — | — |
| Gapex INC | Luis Antonio Jr Leal | — | (925) 687 9860 | HVAC | Concord · Contra Costa County | — | — |
| Garage Door Pros & Automatic Gates | Bar Levy | — | (415) 630 0269 | Other | Pleasant Hill · Contra Costa County | — | — |
| Garage Door Warriors INC | Dvir Meshulami | garagedoorwarriors@gmail.com | (925) 570-2099 | Other | San Ramon · Contra Costa County | — | — |
| Garces Electric | Garces Benavides Carlos | — | (510) 974 9446 | Electricians | San Pablo · Contra Costa County | — | — |
| Garcia Andrew Refrigeration | Garcia Andrew Refrigeration | — | (510) 327 9152 | HVAC | Oakley · Contra Costa County | — | — |
| Garcia Brothers Construction Corp | Rojas Adan Garcia | — | (661) 941 5490 | GC, remodel, ADU | Antioch · Contra Costa County | — | — |
| Garcia Construction Services | Garcia Enrique | — | (925) 584 8735 | GC, remodel, ADU | Brentwood · Contra Costa County | — | — |
| Gardelle Construction | Steven James De La Gardelle | — | (925) 680 6425 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Garden Designs | Garden Designs | — | (925) 595 8791 | Windows, patio, painters | Clayton · Contra Costa County | — | — |
| Garden Girl | Garden Girl | — | (415) 516 8351 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Garden Lights Landscape Development INC | Stephen Winston Lambert | — | (925) 254 4797 | Windows, patio, painters | Orinda · Contra Costa County | — | — |
| Garden Nest Residential Landscape | Jeannie Roseann Johantgen-Fitch | — | (925) 922 0322 | Windows, patio, painters | Orinda · Contra Costa County | — | — |
| Gardencrafters Landscape & Design | Gardencrafters Landscape & Design | — | (925) 998 8870 | Windows, patio, painters | Walnut Creek · Contra Costa County | — | — |
| Gardeners' Guild INC | Michael James Davidson | — | (510) 439 3700 | Windows, patio, painters | Richmond · Contra Costa County | — | — |
| Gardening Solutions Co | Shoshan Yaron | — | (925) 376 7077 | Windows, patio, painters | Moraga · Contra Costa County | — | — |
| Gardner Construction | Mark Wallace Gardner | — | (707) 292 1778 | GC, remodel, ADU | Oakley · Contra Costa County | — | — |
| Gardner Mechanical | Adell Gardner | — | (925) 457 1475 | HVAC | Concord · Contra Costa County | — | — |
| Garez INC DBA Alliance Bath Reglazing | Daniel Ramon Garcia | — | (925) 679 7532 | Other | Brentwood · Contra Costa County | — | — |
| Gary Carl Camozzi | Gary Carl Camozzi | — | (925) 352 7058 | Other | Pleasant Hill · Contra Costa County | — | — |
| Gary Wallace Electric INC | Gary Alan Wallace | — | (510) 375 4400 | Electricians | Walnut Creek · Contra Costa County | — | — |
| Gasca Corp | Juan Carlos Gasca | — | (925) 566 4327 | GC, remodel, ADU | Concord · Contra Costa County | — | — |
| Gasca Landcape | Gasca Landcape | — | (510) 301 1971 | Windows, patio, painters | Hercules · Contra Costa County | — | — |
| Gate Smith | Gate Smith | — | (925) 216 4734 | Other | Walnut Creek · Contra Costa County | — | — |
| Gayler Design Build INC | Darlene Mark Gayler | — | (925) 820 0185 | GC, remodel, ADU | Danville · Contra Costa County | — | — |