| 1 Step By Step Construction | Tony D'arcy Muir | — | (925) 597 4648 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| 1-800 Water Damage Of Solano County | 1-800 Water Damage Of Solano County | info@1800waterdamage.com | (800) 928-3732 | Restoration | Fairfield · Solano County | — | — |
| 1st Choice Electric Service | James Dale Smith | 1stchoiceelectricservice@gmail.com | (415) 328 5711 | Electricians | Fairfield · Solano County | — | — |
| 3-d Plumbing | Glen William Dart | — | (707) 628 9947 | Other | Rio Vista · Solano County | — | — |
| 3G Landscape LLC | Diego Quintero Garcia | — | (510) 387 9996 | Windows, patio, painters | Fairfield · Solano County | — | — |
| 4 K Construction | Eliseo Castro Jr Garcia | — | (707) 704 9860 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| 4 Seasons Pools INC | Castillo Nuno Rene Del | — | (707) 803 1975 | Pool | Vacaville · Solano County | — | — |
| 425 General Engineering INC | Alonso Ojeda | info@general-engineering.com | (510) 342 8013 | Other | Vacaville · Solano County | — | — |
| 4L Artistic Tile | Rudin Luis Roche | — | (415) 596 7043 | Other | Vallejo · Solano County | — | — |
| 8A Renovation | 8A Renovation | — | (707) 337 5976 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| A & J Blinds | A & J Blinds | impallari@gmail.com | (707) 974 9411 | Windows, patio, painters | Vacaville · Solano County | — | — |
| A & K Roofing | George David Padilla | — | (707) 425 1871 | Other roofers | Fairfield · Solano County | — | — |
| A & M Electric | Mario Miles Payan | — | (707) 446 2127 | Electricians | Vacaville · Solano County | — | — |
| A & S Floors | A & S Floors | asf@asfloors.com | (707) 747 4776 | GC, remodel, ADU | Benicia · Solano County | — | — |
| A & S Quality Construction INC | Diana Berenice Silva | — | (707) 880 4471 | GC, remodel, ADU | Dixon · Solano County | — | — |
| A - 1 Cabinets | A - 1 Cabinets | — | (707) 678 1551 | Other | Dixon · Solano County | — | — |
| A And M Flooring Design | Benjamin Charles Rowe | — | (209) 577 1035 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| A B - Pro | A B - Pro | — | (209) 968 7655 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| A B C Plumbing | A B C Plumbing | john@abcplumbing.com | (707) 452 1364 | Other | Vacaville · Solano County | — | — |
| A B Fencing | A B Fencing | — | (707) 864 8629 | Other | Fairfield · Solano County | — | — |
| A Better Electrical Company INC | Jayson Daniel Hinton | — | (707) 230 6701 | Electricians | Vacaville · Solano County | — | — |
| A C A Remodeling Design | A C A Remodeling Design | — | (925) 200 0045 | GC, remodel, ADU | Vacaville · Solano County | — | — |
| A C G Glass Mirror | A C G Glass Mirror | — | (707) 429 4996 | Windows, patio, painters | Fairfield · Solano County | — | — |
| A Climate Control | A Climate Control | — | (707) 816 1776 | HVAC | Vacaville · Solano County | — | — |
| A D C Electric | Antonio David Campos | adcelectric24@gmail.com | (510) 837 1894 | Electricians | Fairfield · Solano County | — | — |
| A David Home Repairs / Improvement | Albert Aguilus David | — | (707) 315 0763 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| A E Electric | Anderson Eduviges Rafael Godoy | — | (415) 860 7161 | Electricians | Vallejo · Solano County | — | — |
| A G A Tile Stone | A G A Tile Stone | — | (415) 827 6775 | Other | Vallejo · Solano County | — | — |
| A G Plastering | A G Plastering | — | (925) 642 0376 | Other | Fairfield · Solano County | — | — |
| A Glass & Mirror Company Corp | Angelo Frank Ii Lugo | — | (707) 326 9990 | Windows, patio, painters | Vacaville · Solano County | — | — |
| A M Access Control INC | Martin Hernandez | — | (800) 421 1924 | Other | Fairfield · Solano County | — | — |
| A Maravilla Construction INC | David Ignacio Vazquez | — | (707) 803 3287 | GC, remodel, ADU | Fairfield · Solano County | — | — |
| A P H Construction | Alex Paul Hill | — | (530) 802 6333 | Electricians | Rio Vista · Solano County | — | — |
| A R Construction | Bruce Everett Sheppard | — | (707) 333 7143 | GC, remodel, ADU | Vallejo · Solano County | — | — |
| A R M S Rooter & Plumbing Services | Angel Ramos Martinez | — | (707) 438 2767 | Other | Suisun City · Solano County | — | — |
| A Reyes Construction INC | Delgado Alfredo Reyes | — | (510) 778 5648 | GC, remodel, ADU | Vacaville · Solano County | — | — |
| A Robledo Construction General Engineering INC | Robledo Alvaro | — | (707) 492 9508 | Other | Fairfield · Solano County | — | — |
| A S Fire Protection | A S Fire Protection | micah@micahrich.com | (650) 430 1527 | Other | Benicia · Solano County | — | — |
| A Squared Construction INC | Joseph David Ballinger | — | (925) 826 5727 | GC, remodel, ADU | Benicia · Solano County | — | — |
| A T O M Plumbing | A T O M Plumbing | — | (510) 565 9550 | Other | Vallejo · Solano County | — | — |