The decision to have reconstructive surgery was made after Sandoval met with Dr. Neal ElAttrache on Wednesday in Los Angeles. He will have the procedure in early September.
Sandoval, 33, hit .269 with 14 home runs and 41 RBIs in 107 games for the Giants this season.
The Giants had placed him on the 10-day injured list earlier this month with elbow inflammation, a condition manager Bruce Bochy said has bothered Sandoval to varying degrees for several years.
“He is in pain,” Bochy said. “This has flared up before, but not quite like this. Sometimes it goes away in two or three days, and other times it’s lingered. This time we can’t get it to go away.”
Although Tommy John surgery is more commonly associated with pitchers, a number of position players have also undergone the procedure in recent years, including Salvador Perez, Didi Gregorius, Corey Seager, Travis d’Arnaud and Gleyber Torres.
A member of the Giants’ three World Series championship teams from 2010 to 2014, Sandoval has been a revelation since returning to San Francisco in 2017 after being released by the Boston Red Sox.
He’s in the last year of a five-year, $95 million contract he signed with Boston in 2014, the bulk of which is being paid by the Red Sox.
Information from The Associated Press was used in this report.