The actor will take on an unnamed role in director Peter Landesman's President John F Kennedy assassination movie, reports Deadline.
The film centres around the Dallas hospital to which JFK was brought to in the hours following his fatal shooting on November 22, 1963.
Welling will join an ensemble cast which features Paul Giamatti, Billy Bob Thornton, Jacki Weaver, Zac Efron, Marcia Gay Harden, James Badge Dale, Jackie Earle Haley, Colin Hanks, David Harbour and Ron Livingston.
The film has been based on Vincent Bugliosi's book Reclaiming History: The Assassination of President John F Kennedy.
Parkland is scheduled for release later in 2013 to mark the 50th anniversary of Kennedy's assassination.