The actor revealed last week that he will not be returning for a sixth season as Dr George O’Malley on Grey’s Anatomy.
Knight will be starring as Leo Frank in the Tony Award-winning production about a real-life Jewish Southerner who was falsely hanged for a crime in 1915, E! reports.
"I am very fortunate to return to the theatre playing Leo Frank in this incredible, acclaimed production of Parade," he told the Los Angeles Times.
"After a five-year break, it feels great to be on stage again."
His previous stage credits include the 2001 revival of Noises Off, opposite Patti LuPone, while he also featured on the New York stage in the 2004 off-Broadway drama Boy.
Parade will open on October 4 in Los Angeles.