Roberts made the announcement Sunday, one day after beginning a rehabilitation assignment with Class A Aberdeen.
Roberts says the injury didn't improve in the fashion he would have hoped. He expects to have the operation in the next seven or 10 days.
Following a rehabilitation period of four to six months, Roberts intends to work toward returning to the Orioles in 2013.
Roberts missed the start of the season with a concussion. He returned on June 12 and got three hits against Pittsburgh but was batting .182 in 17 games before going on the disabled list July 3.
The two-time All-Star has played in only 115 games over the last three seasons.