Strasburg (15-5) had been scheduled to end his campaign sometime this month. However, the team decided to make the move after a rocky start for the 24-year-old right-hander on Friday.
Strasburg did not make it out of the third inning in a 9-7 loss to the Florida Marlins. Strasburg allowed five runs on six hits and three walks in what was to be his final game of his comeback season after Tommy John surgery.
"He's had a great year," said manager Davey Johnson. "My job is to do what's best for the player. This is what's best."
Strasburg ended the year with 159 1/3 innings pitched. The Nationals had indicated earlier they planned to limit his innings at somewhere around 180 even though the Nats were in playoff contention.
John Lannan was expected to take Strasburg's spot in the rotation. The left-hander spent most of the season at Triple-A Syracuse.