Allen, who made his announcement Tuesday on social media, will not suit up for the Badgers in their upcoming bowl game, a team spokesman confirmed to ESPN.
The Fond du Lac, Wisconsin, native finishes his Wisconsin career with 3,494 rushing yards and 35 touchdowns on 597 attempts. He eclipsed 1,200 rushing yards in each of his first two seasons, earning second-team All-Big Ten honors, and could receive a third all-league recognition when offense awards are announced Wednesday.
"Playing for Wisconsin and wearing the motion W has been one of the greatest honors of my life," Allen said in a video announcing his NFL departure. "I was proud of carry on the incredible legacy of RBU and follow in the footsteps of so many great running backs. I've tried to represent UW and my state with dignity and pride."
Allen joined Ron Dayne (1996), James White (2010) and Jonathan Taylor (2017) as the only Wisconsin running backs to eclipse 1,000 rushing yards as true freshmen. He had 15 games of 100 rushing yards or more in his first two seasons before being limited by injuries twice this fall. Allen had 12 or fewer carries in four games, including only three in a Nov. 11 loss to Northwestern. But he finished strong with 165 rushing yards and two touchdowns in Saturday's rivalry win over Minnesota.
ESPN's Mel Kiper lists Allen as his No. 10 draft-eligible running back, and ESPN's Matt Miller listed Allen at No. 4 on his running back rankings at the end of October.