Tucker spent last season as the head coach at Colorado, guiding the Buffaloes to a 5-7 record, including a 3-6 mark in Pac-12 play.
The 48-year-old tweeted last week that he was committed to building the Colorado program. But on Wednesday, the Buffaloes stated that Tucker had resigned, appearing to confirm his move to Michigan State.
"We are disappointed to see Coach Tucker leave," Colorado athletic director Rick George said in a statement. "We are excited about the upward trajectory of our football program and we'll get to work immediately hiring the next head coach to build on our momentum and lead our young men."
Michigan State got its man by offering an increased coaching salary pool and a substantial increase to the Spartans' strength and conditioning budget, and more than doubling Tucker's $2.7-million salary with the Buffaloes, Feldman reports.
Tucker served as the defensive coordinator at Georgia from 2016 to 2018 before joining Colorado in December 2018. He was Alabama's DC in 2015 and has served on the defensive staff at Ohio State, LSU, and Miami (Ohio). He was also a graduate assistant at Michigan State in 1997 and 1998.
Tucker comes with NFL experience, too, as he was the defensive coordinator for the Chicago Bears, Cleveland Browns, and Jacksonville Jaguars. He served as Jacksonville's interim head coach for the end of the 2011 season, compiling a 2-3 record.
The hiring comes a little over a week after Dantonio made the surprising decision to step down following 13 seasons at Michigan State. The former head coach went 114-57 with the Spartans and earned bowl appearances in 12 of 13 years, including a Rose Bowl victory in 2014.