However, it wasn't immediately known whether he quit or was asked to leave.
Trump's campaign announced the departure, saying Stone -- who was an aide to former president Richard Nixon -- was fired Friday because he was supposedly trying to attract attention for himself instead of Trump.
"I terminated Roger Stone last night because he no longer serves a useful function for my campaign," Trump told the Washington Post Saturday. "I really don't want publicity seekers who want to be on magazines or who are out for themselves."
Stone's camp, however, says the Republican strategist resigned Saturday morning in advance of Trump's campaign announcement. Stone himself corroborated that claim via Twitter -- implying that his departure may have been facilitated by Trump's public spat with Fox News host Megyn Kelly.
"Sorry [Trump] didn't fire me. I fired Trump. Diasagree with diversion to food fight with [Kelly] away core issue messages," the tweet said.
Kelly and Trump mildly butted heads during Thursday night's GOP debate, which was broadcast and moderated by Fox News, when she asked him about prior remarks that disparaged women.