Fan Sophie Wilkinson was seriously injured in a car crash last year and has been in intensive care in Southampton General Hospital.
Depp agreed to record a voice message as his Pirates of the Caribbean character Jack Sparrow in an attempt to rouse the teenager after her parents wrote asking for help. He also said he would try to visit her.
Her dad Andrew is quoted as saying: "We are looking for the key to wake her up, so we wrote to Johnny and he said he would do the recording in the voice of Jack Sparrow.
"Only this week Sophie moved her right leg, which she has never done before. When we got home my wife and I were jumping for joy!"