Emil Michael, Uber's senior vice-president and a close ally of chief executive Travis Kalanick, is leaving the company, according to reports.
His departure is understood to be one recommendation in a report by former US Attorney General Eric Holder about the company's culture and practices.
Uber said the board had voted unanimously to adopt all the report's recommendations.
However, its contents will not be released until Tuesday.
It is possible Mr Kalanick could be forced to take a leave of absence or have his role altered.
Mr Holder was asked to undertake the review in February after former Uber engineer Susan Fowler made claims of sexual harassment.
James Cakmak, an analyst at Monness Crespi Hardt, said Mr Michael's expected departure reflected Uber's need for a "fall guy" and could help protect Mr Kalanick.
"If Kalanick did leave, we think it would be very difficult for him to come back," Mr Cakmak told Bloomberg.
An Uber insider said the recommendations in Mr Holder's report include introducing more control on spending, human resources and other areas where executives led by Mr Kalanick have had an unusual degree of autonomy for a company of Uber's size.
The San Francisco-based taxi-hailing service has more than 12,000 employees.
Mr Kalanick has earned a reputation as an abrasive leader and was criticised earlier this year after being caught on video berating an Uber driver.
He said in response to the video: "I must fundamentally change as a leader and grow up."
Uber board member Arianna Huffington has said Mr Kalanick needed to change his leadership style from that of a "scrappy entrepreneur" to be more like a "leader of a major global company".
One Uber investor said the board's decisions were a step in the right direction, giving the firm an "opportunity to reboot".