| Road Name: | Thomas Road |
| State: | wa |
| Type: | road |
| Length: | 23 |
| Route: | State Route 21 |
| Est: | 1950s |
| Direction A: | West |
| End A: | Rockingham Road (National Route 1), Kwinana Beach |
| Direction B: | East |
| End B: | South Western Highway (State Route 20), Byford |
Thomas Road is a major west–east road in the far southern suburbs of Perth, Western Australia, connecting Rockingham Road (part of Highway 1) in Kwinana's industrial area with Kwinana's urban area, before bridging Perth's agricultural fringe to meet the South Western Highway in Byford, just south of Armadale.[1] Thomas Road was the terminus of the Kwinana Freeway from 1993 until 2002, and presently serves as the terminus of Tonkin Highway after its extension beyond Albany Highway in 2003.
Thomas Road forms the entirety of State Route 21.[2]