The Republic of Ireland international arrives at Elland Road on a two-year deal having left Reading at the end of June.
The move reunites Hunt with Brian McDermott, his former manager at Reading, where he scored 39 goals in 162 games.
"Noel is a player that I scouted five years ago when he was playing for Dundee United," said McDermott.
"We spent £500,000 on him at the time, and that was money very well spent. He's an infectious character and I'm sure he will engage Leeds United fans with his desire and determination, and never say die attitude.
"He will bring an awful lot to our squad on and off the pitch, and I'm delighted he's chosen to come and play for Leeds."
Hunt joins fellow new arrivals Luke Murphy and Matt Smith in Leeds' squad for the forthcoming Championship season.