Heynckes took over from Carlo Ancelotti at Die Roten in October and has since led them to 15 wins in 16 games across all competitions, lifting them to top spot in the Bundesliga.
In his previous spell at Bayern Heynckes won the treble, claiming the 2013 UEFA Champions League title, Bundesliga title, and DFB-Pokal.
"We've rarely been able to celebrate Christmas in as relaxed a mood as this year," Rummenigge wrote in his end-of-year letter to club members and fans.
"We can be very satisfied with 2017. Last summer we won a fifth Bundesliga title in a row – that's an historic achievement! Even the so-called golden 70s failed to produce such sheer Bavarian dominance, and our team is well on course to extend this streak.
"We're top of the table at the halfway stage of the season for the seventh time in a row, with an 11-point lead over our rivals. I think that's remarkable! We're also on track in the Champions League and DFB Cup.
"Special thanks go to Jupp Heynckes and his coaching staff. Jupp has made a wonderful comeback. We've won 15 of our 16 matches since he returned, and I'm convinced he'll continue to help the team develop after the winter break, even though the mid-season training period is very short this time.
"And I'd also like to thank Carlo Ancelotti, who led us to the aforementioned fifth league title last summer."
