The 24-year-old Harry Potter star and Darke, also an actor, were recently spotted together on a grocery run in New York. A representative for Darke confirms to The Daily Mail that the pair have been dating "for about two years."
Radcliffe and Darke met in 2012 on the set of Kill Your Darlings. Radcliffe had just ended a two-year relationship with production assistant Rosie Coker, and Life & Style reported that Darke was "devastated" when Radcliffe left after a brief fling.
The Kill Your Darlings actors reunited soon after, and have been seen together at various events in the past year. Radcliffe owns an apartment in Manhattan, and currently stars in the Broadway production of The Cripple of Inishmann.
Radcliffe will next star on film in a 2015 adaptation of Frankenstein. Meanwhile, Darke will appear in several 2014 releases, including Sidewalk Traffic, Love & Mercy and The Quitter.