Radcliffe and Coker, a production assistant on Harry Potter and The Half-Blood Prince in 2007, began dating two and a half years ago.
Coker moved to New York to live with Radcliffe while he starred in the hit Broadway show How to Succeed In Business Without Really Trying.
Though Radcliffe has not divulged the reason behind the split, he did acknowledge it when he told the Daily Mail recently: "She is trying to move on."
Radcliffe has thrown himself into acting work since finishing up the Harry Potter series, starring in The Woman in Black, Kill Your Darlings, and most recently Horns.
He may also star in a sequel to The Woman in Black.