| 20/20 Builders | Joel Norman Meltzer | — | (510) 531 0102 | GC, remodel, ADU | Emeryville · Alameda County | — | — |
| 20/20 Painting Company | George Kais Gilou | — | (619) 754 3680 | Windows, patio, painters | La Mesa · San Diego County | — | — |
| 20/20 Reglazing & Refinishing | Martinique Danielle Garcia | — | (760) 396 8558 | Other | Desert Hot Springs · Riverside County | — | — |
| 20/20 Relining & Rooter | Roque Argote | — | (818) 403 8091 | Other | Palmdale · Los Angeles County | — | — |
| 200 Psi Fire Protection Co | Dong Hun Lee | — | (213) 763 0612 | Other | Northridge · Los Angeles County | — | — |
| 2001 Construction Group | Eduardo Max Garaycochea | — | (408) 371 2006 | GC, remodel, ADU | San Jose · Santa Clara County | — | — |
| 2001 Security System And Electrical Works | Joseph Anthony Franco | — | (408) 639 2001 | Electricians | San Jose · Santa Clara County | — | — |
| 2010 Construction Co | Haghnazar Maghen Donay | — | (818) 632 2010 | GC, remodel, ADU | Encino · Los Angeles County | — | — |
| 202 Builders LLC | Raymond Salvador Gutierrez | — | (661) 406 3936 | GC, remodel, ADU | Tehachapi · Kern County | — | — |
| 2020 Building Services DBA Water Blasting Restoration | Salvador Jr Corona | — | (855) 842 2020 | Restoration | Burbank · Los Angeles County | — | — |
| 2020 Demolition And Grading INC | Pablo Ortiz | — | (213) 798 9015 | Other | Riverside · Riverside County | — | — |
| 2020 Electric INC | Hernandez Jaime Ruiz | — | (925) 305 9103 | Electricians | Oakley · Contra Costa County | — | — |
| 2020 Heating & Air INC | Silvia Eufrosina Olivares Montiel | — | (408) 661 9138 | HVAC | San Jose · Santa Clara County | — | — |
| 2020 Universal | 2020 Universal | — | (760) 497 0212 | Windows, patio, painters | Vista · San Diego County | — | — |
| 203K Contractors INC | Aaron Ron Baldwin | — | (323) 309 9722 | GC, remodel, ADU | Los Angeles · Los Angeles County | — | — |
| 2040 Builders | Tariq Ezzat Ayyad | — | (415) 815 7992 | GC, remodel, ADU | San Francisco · San Francisco County | — | — |
| 2050 Innovation Construction | Demetrius Dwayne Esclovon | — | (510) 313 8556 | GC, remodel, ADU | Berkeley · Alameda County | — | — |
| 209 Lath & Plastering | 209 Lath & Plastering | — | (209) 401 3849 | Other | Stockton · San Joaquin County | — | — |
| 209 Pavement | Elizabeth Marie Vanderveen | — | (209) 985 9581 | GC, remodel, ADU | Modesto · Stanislaus County | — | — |
| 209 Plumbing | 209 Plumbing | — | (209) 687 4367 | Other | Ripon · San Joaquin County | — | — |
| 20th Century Air INC | Scott Robert Baker | — | (714) 450 5060 | HVAC | Murrieta · Riverside County | — | — |
| 20th Century Construction INC | David Bruce Siegel | — | (818) 887 2084 | GC, remodel, ADU | Calabasas · Los Angeles County | — | — |
| 20th Century Pools-palm Springs INC | Jose Manuel Mendoza | — | (951) 757 2347 | GC, remodel, ADU | Wildomar · Riverside County | — | — |
| 21 Century Tile And Stone INC | Gustavo Ernesto Ortiz | — | (619) 748 0924 | Other | San Ysidro · San Diego County | — | — |
| 21 Degrees Construction | Martinez Hernandez Sergio | — | (760) 519 7414 | GC, remodel, ADU | Escondido · San Diego County | — | — |
| 21 Plumbing | 21 Plumbing | — | (909) 477 1600 | Other | Yucaipa · San Bernardino County | — | — |
| 21 Retrofit & Steel INC | Tony Jeong Kim | — | (213) 999 6286 | GC, remodel, ADU | Carson · Los Angeles County | — | — |
| 21 St Century Remodeling INC | Gabay Yosi | — | (818) 620 7190 | GC, remodel, ADU | Calabasas · Los Angeles County | — | — |
| 210 Construction | James Anthony Jr Phillips | — | (909) 436 0596 | GC, remodel, ADU | Lake Arrowhead · San Bernardino County | — | — |
| 211 Plumbing & Drains INC | Jose Alexis Alviter Arzate | — | (760) 557 9413 | Other | Oceanside · San Diego County | — | — |
| 21M Construction Co | Francisco Javier Oseguera | — | (619) 215 3335 | GC, remodel, ADU | San Diego · San Diego County | — | — |
| 21pools INC | Cory Joe Reeder | — | (559) 786 6260 | Pool | Visalia · Tulare County | — | — |
| 21st Century Air Master H V A C INC | Seyed Fakhridden Alemi | — | (949) 444 8889 | HVAC | Aliso Viejo · Orange County | — | — |
| 21st Century Builder | 21st Century Builder | — | (707) 975 6441 | GC, remodel, ADU | Petaluma · Sonoma County | — | — |
| 21st Century Design | 21st Century Design | — | (619) 708 6725 | GC, remodel, ADU | Escondido · San Diego County | — | — |
| 21st Century Electric | Paul Harry Bussell | typesetit@att.net | (760) 809 8285 | Electricians | Encinitas · San Diego County | — | — |
| 21st Century Electric M | Aharon Marcel Aharonian | support@21stcenturyelectricm.com | (323) 496 4155 | Electricians | North Hollywood · Los Angeles County | — | — |
| 21st Century Floors | 21st Century Floors | — | (707) 467 0181 | Other | Ukiah · Mendocino County | — | — |
| 21st Century Home Improvement Painting & Roofing | Mark Francis Newbury | — | (415) 974 1234 | Other roofers | San Francisco · San Francisco County | — | — |
| 21st Century Lihtc Construction INC | Scott Nichols Mason | — | (323) 231 4174 | GC, remodel, ADU | Burbank · Los Angeles County | — | — |