NFL spokesman Brian McCarthy confirmed to ESPN's Jeff Darlington that the "allegation was shared with the NFL and we have reached out to Uber to request any information they may have."
The league's investigation was first reported Friday by BuzzFeed News, which viewed a letter it said was sent from NFL executive Lisa Friel to the Uber driver.
"The League has been informed that you may have been the victim of such a violation perpetrated by Tampa Bay Buccaneers player Jameis Winston," Friel wrote in the letter. "The league takes allegations of this nature very seriously and has opened an investigation into this matter."
Winston denied the allegations, saying in a statement Friday that the "accusation is false."
"A news organization has published a story about me regarding an alleged incident involving a female Uber driver from approximately two years ago," Winston said in the statement. "The story falsely accuses me of making inappropriate contact with this driver. I believe the driver was confused as to the number of passengers in the car and who was sitting next to her. The accusation is false, and given the nature of the allegation and increased awareness and consideration of these types of matters, I am addressing this false report immediately. At the time of the alleged incident, I denied the allegations to Uber, yet they still decided to suspend my account.
"I am supportive of the national movement to raise awareness and develop better responses to the concerns of parties who find themselves in these types of situations, but this accusation is false. While I am certain that I did not make any inappropriate contact, I don't want to engage in a battle with the driver and I regret if my demeanor or presence made her uncomfortable in any way."
The driver, who declined to give her name, told BuzzFeed News that she picked Winston up at around 2 a.m. on March 13, 2016, in Scottsdale, Arizona. Winston asked her to stop at a drive-thru restaurant during the ride, and while in line, the driver said Winston reached over and "grabbed" her crotch for three to five seconds, only removing his hand when she said something. Winston was the only passenger in the car, the driver said.
The driver told BuzzFeed News that she reported the incident to Uber at the time. An Uber spokesman told ESPN's Jenna Laine that the "behavior the driver reported is disturbing and wrong. The rider was permanently removed from the app shortly after we learned of the incident."
Winston was in Arizona for Kurt Warner's annual "Ultimate Football Experience" event during the weekend that the incident allegedly occurred. Winston's representative, Russ Spielman, also denied the allegations in a statement to BuzzFeed News.
"We categorically deny this allegation," Spielman said. "It is our understanding the Uber driver was unable to identify the specific individual who allegedly touched this driver inappropriately. The only reason his name is being dragged into this is that his Uber account was used to call the ride."
A Scottsdale Police Department spokesperson told Laine that the driver "did not call us or file a report with us." The Phoenix Police Department also confirmed to Laine that they were not contacted about an incident involving Winston and an Uber driver.
The Buccaneers also released a statement Friday saying that they are gathering information about the situation. Bucs coach Dirk Koetter said at his availability earlier Friday he was "just finding out" about the allegation.
"We take these matters seriously and are fully supportive of the investigation that is being conducted by the NFL," the team said.
Winston hasn't practiced all week because of a shoulder injury but was present Friday during the team's workout.
Winston was accused of sexually assaulting a Florida State student in 2012. He acknowledged having sex with the woman but said it was consensual. The allegations were investigated by Tallahassee police but charges were never filed, and the case was closed in December 2013, just over a week before Winston won the Heisman Trophy.
In 2015, the woman in the case, Erica Kinsman, filed a civil suit against Winston, who countersued. The suits were settled out of court in 2016 and specifics were not released.
Florida State agreed in January 2016 to pay Kinsman $950,000 as part of a Title IX lawsuit she filed against the school for its handling of her complaint. The school also agreed to five years of sexual assault awareness programs but did not admit liability as part of the settlement.
Winston also was suspended for Florida State's game against Clemson in September 2014 after he stood on a table in the university student union and shouted a sexually explicit internet meme.