The deadline for teams to declare the fifth-year option for players drafted in 2015 is May 3. Winston, who was picked first that year, will earn $20.922 million.
The news was first reported by the Tampa Bay Times.
Winston, 24, has started 45 games for the Bucs in three seasons, throwing for more than 4,000 yards in each of his past two years.
He led the Bucs to a 9-7 record in 2016 -- their first winning season since 2010 -- but struggled with a shoulder injury to his throwing arm in 2017, with the Bucs falling to 5-11.