British media reported that the transfer fee was around 17.4 million pounds.
The 26-year-old, who has two international caps, joined Hoffenheim in 2023, scoring four goals and registering six assists in 71 appearances.
"My style of play, I would say, I am an aggressive player. I am good in duels. I am good at anticipating passes from the opponents, and it would be good for the Premier League," Stach said in a statement.
Leeds start their Premier League campaign at home to Everton on August 18th.