Speaking after the move, Diomande expressed his excitement at joining the German club.
"I'm very happy that my future lies in Leipzig. It's a great honor for me to be able to play for this great club in the future," the 18-year-old said in the club's official statement.
"The management wants to play fast-paced, attacking football, which suits my abilities very well. I can't wait to get to know my teammates and the entire staff and to be on the pitch with them soon."