Rudd will play Leslie's (Amy Poehler) opponent in the race for city council. Hahn, who will join the series for a multi-episode arc, will be his adviser.
Rudd's Broadway credits include The Last Night of Ballyhoo, Twelfth Night, The Play What I Wrote and Three Days of Rain. Hahn has been seen on Broadway in Boeing-Boeing.
"Parks and Recreation" airs Thursday nights at 8:30 PM ET on NBC.