The former Germany international, 49, has signed a contract with Augsburg until the end of the 2019-20 season.
"FC Augsburg have developed incredibly in recent years," said Lehmann.
"This is a brilliant opportunity for me to work as an assistant coach in the Bundesliga and to help the players reach their potential on the pitch."
Lehmann will attend his first Augsburg training session on Tuesday.
Head coach Manuel Baum said: "He is an expert of the game, who possesses a lot of experience.
"I look forward to working with him and I'm sure he will enhance our team and our work on and off the pitch."