The 24-year-old has teamed back up with Leeds manager Neil Warnock, his manager at former club Crystal Palace, initially on loan until January.
"I've known Ryan for many years and was a big fan of his at Crystal Palace," Warnock told the club's official website. "All credit to him to come back into my thoughts.
"I'm looking for a player of his quality. I don't know if he can do it at this level yet, but he offers something different in the squad. He can give us an option where he could change a game."
Hall, linked with both Peterborough and Blackpool before sealing his move to Yorkshire, was sentenced to 20 weeks in prison in March 2011, later reduced to 12 weeks and suspended for a year, following an incident outside a Southend nightclub.
Warnock added: "I'm not right every time, but I do forgive and forget. I always remember one player who had everything, but had a few off-the-field problems. Ryan has to put his own house in order, but this is a great opportunity for him. He needs to get away from the south and grasp the opportunity we've given him."
- Sports & Recreation