| 1 Day Aluminum Gutters | 1 Day Aluminum Gutters | — | (858) 472 6279 | Other | Poway · San Diego County | — | — |
| 1-stop Integrated Solutions LLC | Luis Alberto Reyna Gaytan | — | (760) 705 5639 | Other | Escondido · San Diego County | — | — |
| 101 Hardwood Flooring | 101 Hardwood Flooring | — | (760) 450 7429 | Other | Carlsbad · San Diego County | — | — |
| 101 Stucco INC | John Hugh Coutts | — | (760) 801 2639 | Other | Encinitas · San Diego County | — | — |
| 1224 INC | Jamison Scott Persons | — | (619) 206 0811 | Other | San Diego · San Diego County | — | — |
| 123 Floor | James Wendell Cantwell | sdjim6@gmail.com | (858) 583 0377 | Other | San Diego · San Diego County | — | — |
| 1904 Garage Doors & Gates INC | Alexander Joseph Johnson | info@garagedoorsgates.com | (619) 962 1564 | Other | San Diego · San Diego County | — | — |
| 1st Aid Drainage & Plumbing INC | Ricardo Bernal | — | (619) 454 2704 | Other | Lemon Grove · San Diego County | — | — |
| 1st Choice Drywall INC | Rogelio Silva-Espitia | — | (619) 799 8404 | Other | Lemon Grove · San Diego County | — | — |
| 1st Class Plumbing | 1st Class Plumbing | — | (760) 925 1336 | Other | Escondido · San Diego County | — | — |
| 1st First Prodoor | Jesse Calderon | — | (619) 942 2570 | Other | El Cajon · San Diego County | — | — |
| 1up Drywall | Luis Antonio Garcia | — | (760) 532 6656 | Other | Escondido · San Diego County | — | — |
| 21 Century Tile And Stone INC | Gustavo Ernesto Ortiz | — | (619) 748 0924 | Other | San Ysidro · San Diego County | — | — |
| 211 Plumbing & Drains INC | Jose Alexis Alviter Arzate | — | (760) 557 9413 | Other | Oceanside · San Diego County | — | — |
| 24 / 7 Trucking INC | Kevin Darrell Gilliam | — | (619) 262 5171 | Other | San Diego · San Diego County | — | — |
| 24 Hour Bathtub Refinishers | Miguel Cano Lopez | — | (619) 990 9944 | Other | La Mesa · San Diego County | — | — |
| 24 Hour Plumbing And Leak Detection | Tuan Ba Pham | — | (619) 885 5960 | Other | San Diego · San Diego County | — | — |
| 24/7 Thuro-dry Flood Services | Ron Allen Barnes | thurodry1@gmail.com | (858) 270 5600 | Other | San Diego · San Diego County | — | — |
| 2nd Gen Plumbing INC | Lopez Ivan Fernandez | — | (619) 607 8855 | Other | San Diego · San Diego County | — | — |
| 3 Blind Mice Window Coverings INC | Scot Thomas Dietz | — | (858) 452 6100 | Other | San Diego · San Diego County | — | — |
| 3 C Framing | 3 C Framing | — | (760) 297 8532 | Other | San Marcos · San Diego County | — | — |
| 3 In 1 Bathtub And Kitchen Refinishing INC | Estrada Heriberto | — | (619) 575 9253 | Other | Chula Vista · San Diego County | — | — |
| 3-d Mobile Home Services INC | David Glenn Mckee | — | (760) 294 8209 | Other | Escondido · San Diego County | — | — |
| 321 Plumbing INC | Benito Estrada Chavez | — | (760) 215 9520 | Other | Escondido · San Diego County | — | — |
| 345 Concrete INC | Jose De Jesus Lopez Aguilar | — | (858) 401 0579 | Other | El Cajon · San Diego County | — | — |
| 365 Plumbing INC | Fares Belanteur | — | (619) 724 8550 | Other | La Mesa · San Diego County | — | — |
| 3:23 Metal Works INC | Christopher Robert Keys | support@metalworks.com | (442) 320 3237 | Other | Fallbrook · San Diego County | — | — |
| 3dl Forever Flooring INC | De Leon Daniel Diaz | — | (619) 292 5570 | Other | Spring Valley · San Diego County | — | — |
| 3G Engineering Corp | Jose Adolfo Gastelo Pimentel | — | (619) 495 6442 | Other | Spring Valley · San Diego County | — | — |
| 4 Brothers Drywall INC | Candelario Larios | — | (619) 642 1941 | Other | Ramona · San Diego County | — | — |
| 481 Plumb | 481 Plumb | — | (858) 342 5796 | Other | Del Mar · San Diego County | — | — |
| 49 Plumbing | 49 Plumbing | — | (916) 825 5230 | Other | La Jolla · San Diego County | — | — |
| 4G Grading | Gregory Douglas Garner | — | (760) 522 8920 | Other | Ramona · San Diego County | — | — |
| 4liberty INC | Srpouhi L Galpchian | — | (619) 559 1913 | Other | Encinitas · San Diego County | — | — |
| 4th Dimension Drywall | 4th Dimension Drywall | — | (858) 568 3337 | Other | El Cajon · San Diego County | — | — |
| 5 North Media | Robert Thomas Jr Bobuk | — | (858) 621 2155 | Other | San Diego · San Diego County | — | — |
| 5-18 Synthetic Products | Ezequiel Resendiz | — | (760) 594 4301 | Other | Vista · San Diego County | — | — |
| 6-2 Plumbing INC | Sixto Pablo Velazquez | — | (619) 894 3721 | Other | El Cajon · San Diego County | — | — |
| 619 Santa Drywall INC | Daria Moreno | — | (619) 551 0592 | Other | Lemon Grove · San Diego County | — | — |
| 619-m Floor Covering | 619-m Floor Covering | — | (619) 791 5859 | Other | National City · San Diego County | — | — |