The 34-year-old actor spent the afternoon in Maui with the tanned, toned brunette, and they looked cool in a pair of matching shades, reported Us magazine.
The actor went shirtless while she opted for a pair of peach shorts and colorful bikini top.
Bartha previously dated Ashley Olsen for two years before the pair split in March 2011.
His hit show, 'The New Normal', will return this season on Tuesday on NBC.