“We regret the news about Maria Sharapova. Until more details are known and we can analyse the situation, we have decided to suspend planned activities (with her),” said Porsche in a statement.
The 28-year-old Sharapova, who has won five Grand Slam titles in her career, signed a three-year deal to be brand ambassador for Porsche in April 2013.
The Russian also won the WTA indoor tournament in Stuttgart, which is sponsored by the car manufacturers, in 2012, 2013 and 2014, with the champion driving off in a brand-new sports car.
Porsche joins Swiss watchmaker TAG Heuer and US sportswear giant Nike, who said they were halting their relationship with Sharapova.
Sharapova announced Monday that she had tested positive for Meldonium, a drug she said she had been taking since 2006 but was only added to the banned list this year.