Heynckes has overseen 15 wins from 16 matches in all competitions since returning to the club for a fourth time on 6 October in place of Carlo Ancelotti, transforming a five-point deficit at the top of the Bundesliga standings to an 11-point lead.
"We've rarely been able to celebrate Christmas in as relaxed a mood as this year," Rummenigge wrote. "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."
Watch: Bayern got the better of Stuttgart in their final Bundesliga outing of 2017
Bayern, who have gone on to win the league in five of the last six seasons in which they have topped the standings at Christmas, are chasing an unprecedented sixth successive Bundesliga title and 27th overall.
The defending champions resume their title defence away to fourth-placed Bayer Leverkusen on 12 January 2018 (kick-off 20:30CET/19:30GMT).