In 1993 he joined the Daimler-Benz AG as a trainee in the International Management Associate Program. In 1995 Källenius headed a team and later a department at the Corporate Controlling unit of Mercedes-Benz U.S. International Inc., Tuscaloosa, USA. Returning to Stuttgart he became the head of procurement for Mercedes-Benz Cars Engine Emission Management in 2000. In 2001 he was appointed Director of Project Alliance at Procurement Mercedes-Benz Cars. In 2002 he took over the position of Director of Procurement Mercedes-Benz Cars Powertrain.
In 2003 Källenius became the Executive Director, Operations at McLaren Automotive Ltd. in Woking, UK. He also spent the next phase of his career in the United Kingdom, where he was appointed Managing Director of Mercedes-Benz HighPerformanceEngines Ltd. in Brixworth in 2005.
In 2009 Källenius headed Mercedes-Benz U.S. International Inc. in Tuscaloosa, USA, where he served as the company’s Vice President and CEO. He returned to Germany in 2010 to become Vice President and Managing Director of Mercedes-AMG GmbH in Affalterbach. In 2013 he was appointed the group president responsible for Marketing & Sales at Mercedes-Benz Cars.
On January 1, 2015 Källenius was appointed to the Daimler Board of Management. For two years, he was responsible for Mercedes-Benz Cars Marketing & Sales. In 2017 he took over the Group Research & Mercedes-Benz Cars Development division. On May 22, 2019 Ola Källenius became Chairman of the Board of Management of Daimler AG - now Mercedes-Benz Group AG.