"My duties will transfer to Vice Chairman Jeff Garvey who will serve as chairman," Armstrong said in a release put out by the foundation.
His announcement comes a week after the United States Anti-Doping Agency made public its evidence in a doping case against him.
The agency said Armstrong was at the center of an organized doping program on his Tour de France winning teams.
The report prompted Nike Inc. to announce on Wednesday that it has terminated its contract with Armstrong, Market Watch reported.
The company said the termination was "due to the seemingly insurmountable evidence" that the bicyclist participated in blood doping.
"Nike does not condone the use of illegal performance enhancing drugs in any manner," the company said, adding that it will continue to support the LiveStrong initiatives.