The couple broke up in 2009, but it looks like they're still on speaking terms.
The actress walked up to Jonas, 24, who was sitting alone at a table, and the two looked friendly as they chatted for about 15 minutes, E! Online reported.
Belle wore a halter gown with a plunging neckline and tiered skirt to the event. Jonas had on a classic black tuxedo.
Notable deaths of 2014 [PHOTOS]