The prized instruments were reported stolen from a soundstage at Culver Studios in Culver City, California where Petty and his band were rehearsing.
Petty offered a “no questions asked” $7,500 (£4,700) reward for information leading to their return.
Security guard Daryl Washington was detained after police received a tip that one of the guitars had been sold to a pawn shop in Hollywood for $250 (£156.50).
Posting on his Facebook page, Petty said: “I’m extremely grateful to the Culver City Police Department for a job well done and touched by the outpouring of good wishes and concern from our fans and friends.”
Tom Petty & The Heartbreakers will make their first visit to the UK in over 20 years in June with dates set for London’s Royal Albert Hall (18th and 20th) and the Isle of Wight Festival (22nd).