Nkemdiche's high school coach, Mickey Conn, confirmed the news to several publications.
The versatile Nkemdiche was said to have decommitted Wednesday night, but he issued a statement at the time saying it wasn't true.
Nkemdiche committed to the Tigers back in June, becoming the third player from his Grayson High School to do so, joining Wayne Gallman, a four-star running back, and David Kamara, a three-star cornerback.
But Nkemdiche's tone changed in August, when he told Scout he intended to take visits to major programs out West.
Last week, Nkemdiche said that despite his commitment, several other schools were still pursuing him.
"Oh yeah, a lot of schools are still out there recruiting me. Ole Miss, Alabama, Florida, and LSU are probably the main ones right now," he told Scout.com's Chad Simmons. "I have not really talked much with any of them, but they are all still on me hard."
|What next for Robert Nkemdiche and Clemson. Go inside to get recruiting analyst Chad Simmons' thoughts on the big news.|
By Wednesday, reports were surfacing that Nkemdiche had backed out of his Clemson word before Thursday's confirmation.
Gallman and Kamara are both still committed to Clemson, with Gallman reaffirming his status on Wednesday.
Ole Miss has been a popular rumored landing spot for Nkemdiche. His older brother Denzel currently plays for the Rebels.
Nkemdiche is listed as a defensive end but also plays running back for his Georgia high school.