He succeeds Hue Jackson, who left the Ravens to become offensive coordinator for the Oakland Raiders.
Zorn was fired from his head coaching position in January by Washington after a 4-12 season.
"Jim played successfully in the NFL for a long time," Coach John Harbaugh said Saturday on the Ravens' Web site. "He knows what quarterbacks go through in this league. He has been a quarterbacks coach and a head coach, and he is familiar with our offense. That's a great resume."
Zorn, 56, was a quarterback with the Green Bay Packers and Seattle Seahawks in an 11-year playing career, and when he retired, was a quarterbacks coach and offensive coordinator for Seattle and Detroit before getting his first head coaching job in 2008 with Washington, where he compiled a 12-20 record.