The actor, who has previously dated Taylor Swift and Reese Witherspoon, was spotted dining with Miller in New York last week (ends14Jun13) and sources tell Us Weekly magazine the couple is a new item.
One diner who caught the pair "making out" during a lunch date tells the publication, "They came in as a couple. They were very quiet and private, Jake seemed into her. They were both dressed down and not easily recognisable."
Reports suggest Gyllenhaal met Miller at his gym.
Back in March (13), the same publication linked Gyllenhaal with another Sports Illustrated model, DiDonato, reporting the couple met during exercise classes in New York.