'Croxley' probably comes from a man called Croc or Croca.
The Three Rivers Museum says the origin is not known; the '-ley', a very common ending in English place names, probably comes from Saxon leah, a woodland clearing. Old spellings include Crokesleya, Crochesle and Crokesley. The station opened in 1925 as Croxley Green and was renamed Croxley in 1949, because another Croxley Green station had opened in 1912.