The 36-year-old, who was released by QPR at the end of last season, has signed a one-year deal with Garry Monk’s Championship side.
Leeds become Green’s fourth club, after making over 200 appearances for both Norwich and West Ham before joining QPR in 2012.
Green told his new side’s website: “This is one of those opportunities where the first phone call asking if you want to come and play for Leeds is a very quick one. It was a ‘yes’ straightaway.
“I’m thrilled to be here. I’ve spoken to the manager and I know what he’s got in store and what he’s planning.”
Green follows Monk’s summer signings in Kyle Bartley, Sporting Lisbon forward Hadi Sacko and Swedish striker Marcus Antonsson to Elland Road.