The couple tied the knot Friday at a private residence in Manhattan followed by dinner at upscale Italian restaurant Il Cantinori, the source said.
Charles, 41, and Flack haven't been very public about their relationship, though they did walk the red carpet together at the 63rd Primetime Emmy Awards in September 2011 and attend the wedding of Alec Baldwin and Hilaria Thomas in June 2012, Us Weekly said Saturday.
Flack is a former ballerina in the corp de ballet and wrote a novel about her experiences called "Bunheads," though it's not related to the ABC Family series of the same name.
Charles was previously in "Sports Night" and "Don't Tell Mom the Babysitter's Dead."
Celebrity Couples of 2014 [PHOTOS]