She reportedly claimed she met Harington in Luxembourg, adding that they slept together on several occasions before and after he married Leslie, also 31, in June.
“The allegations in this story are completely false,” a rep for the actor said.
“He’s never even been to Luxembourg nor has he ever met Olga Vlaslova.”
In September, Harington gushed at the Emmys about how his role as Jon Snow led him to Leslie who played his love interest Ygritte.
“It gave me my future family and my life from here on in,” Harington told reporters in the Emmys press room.
“That’s the main thing it did for me, and it’s changed it completely.”