The third-year sophomore who rewrote the school record book had been expected to enter the draft and is a projected first-round pick.
Haskins said on Twitter on Monday he would forgo his final year of eligibility "after many thoughts and prayers with family and close friends." He wrote that just as it was a boyhood dream to play for Ohio State, he also dreamed of being an NFL quarterback.
His sturdy, 6-foot-3, 220-pound frame, quick release and exceptional accuracy make him a top prospect. He smashed most Ohio State and Big Ten passing records, throwing for a nation-leading 50 touchdowns. He finished third in Heisman Trophy voting behind Oklahoma's Kyler Murray and Alabama's Tua Tagovailoa.
He was the MVP of the Rose Bowl Jan. 1, completing 25 of 37 passes for 251 yards and three touchdowns in the finale for coach Urban Meyer before retirement.
Ryan Day, the new Ohio State coach who worked with Haskins as quarterbacks coach, likened him to Atlanta Falcons quarterback Matt Ryan and former Heisman Trophy winner Sam Bradford. Day coached both in the NFL.
"Those are the two guys I've been around that are in that same category right now -- their anticipation, their accuracy, the way the ball comes off their hand," Day said. "I'd compare him to those two guys."
Haskins' NFL decision was telegraphed by Justin Fields, the Georgia quarterback who announced Friday he was transferring to Ohio State. Haskins said the two talked first, and it was seen as unlikely Fields would have transferred unless Haskins was moving on.
After a redshirt year in 2016, Haskins backed up J.T. Barrett in 2017. After Barrett was injured during the Michigan game, Haskins entered and led the Buckeyes to a comeback victory.
He battled Joe Burrow for the starting job in the spring and secured it when Burrow transferred to LSU last summer. He proceeded to change the Buckeyes into a pass-first team, throwing for more than 400 yards five times, including a career-high 499 in the Big Ten Championship win over Northwestern. That came after he threw for six touchdowns in the 62-39 rout of Michigan the previous week.
He was the Big Ten offensive player of the week a record six times. The only blemish on Haskins' resume is the inexplicable 49-20 loss at unranked Purdue Oct. 20. Haskins passed for 470 yards in the game, primarily because the Boilermakers had shut down Ohio State's run game and forced the Buckeyes to throw 73 times. The loss kept Ohio State out of the College Football Playoff and hurt Haskins' Heisman bid.
His departure will make for another intriguing quarterback derby beginning in spring practice between Fields, a dual-threat player with a big arm, and fleet Tate Martell, who already has two years playing under Day's tutelage. Redshirt freshman Matthew Baldwin also will be in the mix.
Martell, who was the heir apparent before Fields' arrival, said he is determined to stay at Ohio State and win the starting job.