The stars began dating after meeting on the set of the hit fantasy Tv show, while their characters were also romantically involved onscreen.
The couple split in 2013, but they sparked rumours of a reunion when they were spotted arriving at Los Angeles International Airport together last month (Jul14) ahead of an appearance at San Diego's Comic-Con event.
However, Leslie has now confirmed the pair is not back together.
She tells Britain's You magazine, "I'm not in a relationship at the moment. But I'm fine with that. Being single can feel empowering and independence is hugely attractive."
She adds of Harington, "We are still very close."