Series star Blair Underwood revealed to TV Guide that Bart will play the new Chief of Staff when the show returns early next year.
The actor previously played George Williams on ABC's Housewives and has also made guest appearances in recent episodes of 30 Rock and CSI: Miami.
Underwood also hinted that Virginia Madsen's character on the show was based on real-life politician Sarah Palin.
He joked: "She plays a mother from Alaska, who becomes a Senator. So she's a political force from Alaska. Attractive woman. Housewife. From Alaska."
The Event will return to NBC after a three-month break on February 28.