Reithofer, 54, has held the post since September 2006 and has been a member of the BMW board since March 2000, a statement added.
"This step will provide continuity over the years ahead and ensure trust and constructive cooperation between the supervisory board and the management board," it quoted supervisory board chairman Joachim Milberg as saying.
In July, BMW, the world's leading premium automobile manufacturer, hiked its forecast for 2010 sales and earnings, saying that improved conditions on global auto markets had boosted its outlook considerably.
The company now expects to sell more than 1.4 million cars this year, around 10 percent more than the previous forecast.
The BMW statement also quoted Manfred Schoch, head of the automaker's labour representatives, as saying the move "will allow us to maintain the successful cooperation between the management board and the works council."
BMW's shares have gained more than 60 percent since the beginning of the year.
On Wednesday, they showed a gain of 1.11 percent to 51.23 euros in afternoon trading on the Frankfurt stock exchange, while the DAX index of leading stocks was 0.29 percent lower overall.