The schools announced the move after Miami coach Mark Richt announced his decision to retire on Sunday night. Diaz spent three seasons serving as the Hurricanes' defensive coordinator under Richt before being named the next Temple coach on Dec. 13.
"Miami is home. The University of Miami is home. The U has truly been 'the job' for me since I first got into coaching," Diaz said in a news release from the Hurricanes.
"Having worked here over the past three years, I came to understand what it means to be part of 'The U' and came to appreciate the passion and commitment to excellence of all who proudly call themselves Canes. We will restore the football program to its place among the nation's elite and we will do it with hard work, dedicated coaches, and outstanding student-athletes. I'm excited about working with Blake and his team to make that happen."
The Hurricanes ranked No. 2 in total defense in 2018.
Diaz began his coaching career in 1998 as a graduate assistant. The Seminoles won a national championship in 1999. He went on to serve as a graduate assistant with North Carolina State University in 2000 and 2001. He coached NC State safeties and linebackers before joining Middle Tennessee State, serving as defensive coordinator for four seasons.
He also served as the defensive coordinator at Mississippi State, Lousiana Tech and Texas before returning to the Hurricanes.
"This evening, head football coach Manny Diaz called to inform me that he has accepted the head coaching position back at the University of Miami," Temple athletic director Dr. Patrick Kraft said in a release from the school. "We are disappointed that he is leaving, but wish him the best as he returns home."
"We have already launched a national search for a new head football coach and I am confident that we will bring yet another outstanding head coach to North Broad Street. Our student-athletes deserve excellence and stability and we are searching for the coach who can deliver on both."
Richt posted a 26-13 record in three seasons with the Hurricanes.