Simonson was born in Milwaukee but grew up on a farm in the small town of Eagle. After graduating with a B.A. in theatre from Lawrence University, he moved to Madison, Wisconsin for a short period, where he worked with the then fledgling Ark Repertory Theatre. He moved to Chicago in 1983, where he helped found Lifeline Theatre, and eventually worked with the Steppenwolf Theatre Company. He became a member of the theatre's ensemble in 1993.
He holds the distinction of being one of only a handful of directors who has received Tony, Emmy and Oscar nominations.
Simonson now lives in Los Angeles, but often works throughout the United States. In 2004 he married theatre producer Susan Raab; she died of breast cancer in 2006, aged 37. They had one child, Henry Simonson.[2] In 2013, Simonson married actress Sue Cremin.
His recent plays, Lombardi/The Only Thing (Madison Repertory Theatre), Carter's Way (Steppenwolf Theatre)[4] and Slaughterhouse-Five (Godlight Theatre of New York) received premieres in 2008. Honest premiered at Carthage College in 2009 and was then part of Steppenwolf Theatre Company's 5th Annual First Look Repertory of New Work. The Carthage Theatre production, the first commission of their New Play Initiative, traveled to the 2010 American College Theatre Festival (Region 3). Simonson's play Lombardi ran on Broadway from October 2010 to May 2011.[5] In 2018, Simonson was invited back to Carthage College to create the tenth play in their New Play Initiative. That play, Up and Away, also traveled to the 2019 Edinburgh Festival Fringe and the 2019 Region 3 American College Theatre Festival.[6]
