Snyder, 69, who has more football victories than any coach in school history, retired in 2005 after 17 years. When Ron Prince was not retained for the 2009 season, Snyder agreed to return to the job.
Snyder's contract is retroactive to Feb. 1 and his annual salary will reach almost $10 million for the life of the deal.
Prior to Snyder's first tenure with the Wildcats, the school's football team had gone 27 straight games without win. During Snyder's stay, they had a 136-68-1 record and played in a bowl game for 11 straight seasons.
The school's football stadium was renamed in his honor after he stepped down in 2005. During Snyder's three years away from the job, Kansas State went 17-20.