The generous singer made the gesture last year (12) during the band's trip to California on his only day off from work, according to fellow British singer Ed Sheeran.
The Lego House hitmaker insists his friend deserves some credit for his efforts to help the needy, telling American radio station 95.5 Wplj, "I saw him in L.A. about three months ago. He had a day off and he went out... no one knows about this... He went out on his day off and spent like two or three grand on Domino's pizzas and drove around for the whole day just giving it to homeless people.
"I think that's an amazing story. That's pretty cool right?... People write about Harry all the time in a negative way with all his love life and stuff, but he does stuff like that a lot... He's actually a pretty genuine dude... Harry only came into this huge amount of wealth in the past two years, so he doesn't take it for granted at all. He's really generous and likes feeling like he does some good in the world."
Chris Brandon, a spokesperson for the Domino's Pizza chain, has since spoken out to thank Styles for his kindness, saying, "All we really want to say though is thank you to Harry for involving us in such a cool thing that he did. My understanding is that Harry and One Direction have plenty of fans... but they certainly gained a bunch more today from us here at Domino's."