The Mercury in Manhattan (Kan.) was the first to report the news.
Snyder posted a 215-117-1 record over 27 seasons at Kansas State with a pair of Big 12 conference championships and five division titles. The 79-year-old became the fourth active coach to be enshrined in the College Football Hall of Fame in 2015.
The Wildcats finished just 5-7 in 2018, marking Snyder’s first losing season in 13 years.
Snyder engineered the “Manhattan Miracle,” turning around a team mired in a 27-game winless streak before guiding it to a winning record (7-4) just three years later.
He previously retired in 2005, but returned to the sideline after successor Ron Prince was fired three years later.
Snyder’s 215 career victories are the third among active FBS coaches behind Notre Dame’s Brian Kelly (219) and Alabama’s Nick Saban (218).
He has said in the past that he would prefer for his son, Kansas State associate head coach Sean Snyder, to take over once he retires. Other likely candidates include Oregon defensive coordinator Jim Leavitt and Clemson defensive coordinator Brent Venables.
Kansas State’s football stadium was renamed Bill Snyder Family Football Stadium in 2005.