The 25-year-old, who plays Edward Cullen in the Twilight series, was walking around in Los Angeles when he saw a homeless man trying to make some money by playing the strings of a not so great acoustic guitar.
After he put money in a collection tin, he headed to a nearby music store and came out with two guitars under his arms: an electric one for himself and an acoustic red one for the tramp.
Holidaymakers Luke Jones and girlfriend Kirsty Rowlands, 22, who witnessed the scene, told British newspaper The Sun: “We were gobsmacked when he handed the acoustic guitar to the tramp. Robert quickly went back to his car and drove off.”
He continued: “The busker was totally shell-shocked. He had no idea who Robert was – I think he thought the guitar was stolen.
“He was looking left and right, half expecting the police to arrest him. We asked him to play but he couldn’t get his thoughts together.”