The brand's logo, a bright orange ball with the number 76 in blue in the middle, has become a fixture at NASCAR tracks in a relationship that has endured for more than 50 years.
The sponsorship will end after the 2003 season.
The company will supply 76 brand gasoline for all Winston Cup, Busch and Truck series events this year before returning the rights to NASCAR.
It was unclear if ConocoPhillips wanted out of the deal or whether the departure was spurred by a potential NASCAR deal with another supplier.
A statement announcing the company's decision cited "changing business strategies" that left ConocoPhillips "unable to take full advantage of NASCAR's national and international marketing platform."
Jim Hunter, NASCAR vice president for corporate communications, said in a statement that the sanctioning body will look forward to welcoming a new official fuel supplier to NASCAR in 2004.
"We are in the process of identifying a new official fuel supplier and will make an announcement regarding that supplier at the appropriate time."
Sponsorship in sport is just one of the topics to be discussed at SportAccord, the leading industry conference taking place in Madrid between May 12-16.
To find out how YOU can attend, click on the link below to visit the official SportAccord website.
