Rummenigge, speaking at the presentation of Lucas Hernandez on Monday, signed for a record 80 million euros ($90.5 million) from Atletico Madrid, said he was the "best defender in the Bundesliga" and Bayern has the best defence in the league.
"I read that the best German central defender would no longer play for Bayern," said Rummenigge, referring to Hummels. "But in my opinion the best German central defender plays at Bayern Munich, and also, incidentally, for the national team."
Rummenigge was referring to Hummels’ former teammate, Niklas Sule.
The 30-year-old Hummels no longer plays for Germany after being dropped along with Bayern teammates Thomas Muller and Jerome Boateng by coach Joachim Löw in March – a decision Bayern criticized at the time.
Hummels rejoined Dortmund in a deal worth up to 38 million euros ($42.5 million) including bonuses last month.