Sagnol, 40, became a firm fans’ favourite during nine years at the club, during which time he won the Bundesliga five times and the DFB Pokal four times as well as the Champions League and the Club World Cup.
The former France international, who left his position as head coach at Bordeaux in March 2016, has signed a two-year deal with Bayern.
Sagnol, who played for the club between 2000 and 2009, said: “I’m pleased to return to Munich with my family. It is a great honour, Carlo Ancelotti, one of the best and most experienced coaches in world football chose me. I’m happy to work alongside him on his team.”
Sagnol speaks excellent German and has a working knowledge of English, Spanish and Italian. Ancelotti’s son, Davide, will continue his duties in an assistant coaching role.
Ancelotti commented on Sagnol’s appointment saying: “After losing two of my assistants, firstly Paul Clement and then Hermann Gerland, from my training staff, I expressed the desire to sign a replacement for the coming season.”