King, who played nickel back ahead of an injured Vincent Fuller, had played in every game this season and started Sunday.
"Eric King required surgery this morning to fix his fractured forearm," Titans Coach Jeff Fisher said Monday. "It's probably going to be a four- to six-week injury. We'll have to do something with Eric not being available down the stretch."
King spent his first NFL season with the Buffalo Bills in 2005. In 2006, the former fifth-round pick from Wake Forest was claimed off waivers by the Titans just prior to the start of the regular season.
The Titans are tied with the Cleveland Browns, both with 9-6 records, going into their game at Indianapolis Sunday.