The pair, both 34, were spotted stealing kisses together and looking cozy over the weekend at an Art of Elysium event in L.A.
"They have lots of common interests," says another source. "It's still pretty new, but they seem to be having a blast together."
Smart, known for turns in The Butterfly Effect and Varsity Blues, previously dated actor Branden Williams for more than a decade, according to reports. Carter stars on the home improvement show Carter Can.