The operation was Friday at the Mayo Clinic.
Washington says Werth's rehabilitation is expected to take two-to-three months.
The 35-year-old was troubled by his right shoulder in early August, when he sat out a week. He wound up hitting .292 with 16 homers and 82 RBIs in the regular season for the NL East champions, then went 1 for 17 in the playoffs.
Werth has three seasons left on a $126 million, seven-year contract with Washington, which plans to have him switch from right field to left this season in a swap with Bryce Harper.