The 72-year-old retired from football altogether following the 2012/13 season, in which he led the Bavarians to an unprecedented treble of Bundesliga, DFB Cup and UEFA Champions League titles. That haul also helped him scoop the FIFA World Coach of the Year award in 2013.
“I wouldn’t have returned to any other club in the world but Bayern are very close to my heart," Heynckes told the official club website upon his return. "My coaching staff and I will now do everything to bring back successful football for the fans. I’m very much looking forward to this challenge."
Ancelotti was relieved of his duties in the wake of Bayern's disappointing start to the current campaign, with a 3-0 defeat away to Paris Saint-Germain in the Champions League proving to be the final straw for the club's hierarchy.
Watch: Highlights of Bayern's treble-winning season in 2012/13
Assistant coach and former Bayern right-back Willy Sagnol took over the reins of first-team for Matchday 7, a 2-2 draw away to Hertha Berlin that leaves them five points behind Bundesliga leaders Borussia Dortmund.
This will be Heynckes' fourth spell at the club, having previously been at the helm from 1987-1991, for a five-game spell in 2009, and again from 2011-2013.