Stoops, who took over at OU in 1999, was the longest tenured coach in college football. The move follows back-to-back, top-five finishes for the Sooners.
Sooners offensive coordinator Lincoln Riley is expected to take over as head coach of the team.
Sports Illustrated shared the following tweet, including a statement from Coach Stoops saying "now is simply the ideal time" for the transition and that his health was not a factor.
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Stoops, 56, won a national title and 10 Big 12 championships at his only head coaching job. During his tenure, no other team won the Big 12 more than twice.
The coach finishes with a 190-48 record and nine bowl victories – a major turnaround after OU finished sub-.500 the three seasons prior to Stoops' arrival, under head coach John Blake.
Stoops compiled an 11-7 record against the University of Texas, which included a 63-14 win in 2000; a 65-13 win in 2003; a 55-17 win in 2011; and a 63-21 win in 2012. He was also 14-4 against in-state rival Oklahoma State.
Reasons for the move are still unclear, and Stoops may assist OU in a non-coaching capacity, but no further information is available at this time.
This story will continue to be updated as details are released.