Licensed Contractors in Ontario, California
All license data is sourced from the California Contractors State License Board (CSLB). Last data update: April 05, 2026.
Contractors by Trade
Building
(456)
Electrical
(166)
Limited
(119)
Painting
(108)
HVAC
(63)
Roofing
(63)
Plumbing
(61)
Earthwork
(55)
Landscaping
(49)
Welding
(30)
Fire
(28)
Solar
(3)
Sts Plumbing & Rooter Inc
Suspended
License #1140510
C-36
Ontario, CA
Est. 2025
Mastel Construction Llc
Suspended
License #1143404
B
Ontario, CA
Est. 2025
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Licensing Resources
How to verify a contractor license
Deposit and payment rules for California contracts
Home improvement contract requirements