Sumich, 43, a dual premiership player, has been an assistant coach with West Coast for the past 11 seasons.
Fremantle’s general manager of football operations Chris Bond confirmed the appointment.
“Peter will be a valuable addition to our coaching staff,” Bond said.
“With more than 20 years as a player and a coach at the elite level, including premiership success, Peter will bring a wealth of knowledge and experience to the Fremantle Football Club.”
Sumich played 150 games for West Coast from 1989-1997.
He played in the Eagles’ 1992 and 1994 premiership sides and was seven times the club’s leading goal kicker.
He also played 112 games for South Fremantle in the WAFL, and was coach of the Bulldogs from 2001-2002.
Sumich said: “It’s the right decision and the right time to accept this appointment. I’m really looking forward to working with new senior coach Ross Lyon. I’m also relishing both the prospect of such a significant change and the challenges that lay ahead.”
To watch Peter Sumich's media conference from today click here.
