The company said in a statement that it was "surprised" by the revelations that he failed a drug test but applying the provisions of his contract.
"Even if we assume innocent until proven otherwise, we contract with Tyson currently suspended," said adidas.
"adidas has a clear policy about doping and drug use - each of our athletes to enter into an agreement with a clause clearly stating that the agreement will expire by adidas if athletes found guilty of possession or use of drugs or any other substance prohibited by the relevant sports agency that has jurisdiction over the athlete. "
Gay, 30, is one of the four fastest men in history and has a personal best 9.69secs to 19.58secs for the 100m and 200m.
He is the 100m, 200m and 4x100m relay world champion in 2007 and comes three silver half-lap sprint in the 2009 edition but failed to translate that success to the Olympic level through bad luck and injury.
On Sunday, he confirmed that he was informed that he had tested positive for a banned stimulant at the U.S. National Trials in June.
He insists, though, that he "never intentionally or accidentally taken supplements or substances that break the rules".
A second high-profile sprinter, Jamaican Asafa Powell, also confirmed on Sunday that he had failed a drugs test.