Heilmer is the current president of Designworks, a subsidiary of the BMW Group - with design studios in California, Munich and Shanghai - and has been part of the group's design team for 17 years. Heilmer had also been responsible for the interior design of the BMW brand up until 2016.
The move comes as the company reshuffles its design team to lay the foundations for upcoming generations of its vehicles, as part of its new NUMBER ONE > NEXT corporate strategy.
"I am confident that the Mini design team under Oliver Heilmer will implement this vision of the brand in future vehicle models and win over Mini customers," said Adrian van Hooydonk, head of design for the BMW Group.
"The Mini Vision Next 100 (above) provided an impressive demonstration of Mini's future viability. With his design expertise and experience, Oliver Heilmer combines continuity with the freshness and vision MINI stands for."
Meanwhile, current head of Mini exterior design, Christopher Weil, will continue in his role, and interior design will be led by Christian Bauer from June 1.
Heilmer will be succeeded at Designworks by Holger Hampf, who has been a member of the company's management team since 2002, and was responsible for product design up until 2010.