The Boston Red Sox signed veteran right-hander Brad Keller to a one-year contract on Sunday, six days after the Chicago White Sox designated him for assignment.

Keller, 28, elected to become a free agent on Wednesday. He pitched in five games (two starts) in his lone season with Chicago -- the most recent on May 18 -- and was 0-2 with a 4.86 ERA, six walks and 13 strikeouts in 16 2/3 innings.

He pitched for the Kansas City Royals from 2018-23, posting a 38-53 record with one save, a 4.27 ERA, 303 walks and 506 strikeouts in 679 innings over 150 games (114 starts).

In a corresponding move, the Red Sox optioned right-hander Zack Kelly to Triple-A Worcester. Kelly, 29, is 0-1 with a 2.16 ERA, 10 walks and 14 strikeouts in 16 2/3 innings over 11 relief appearances.

Red Sox manager Alex Cora said that Keller will be used as a long reliever. Injuries to the team's pitchers include right-hander Garrett Whitlock, who told reporters on Saturday that he will miss the remainder of the season to undergo an elbow procedure.

"(Keller has) got good stuff, it's interesting," Cora said Sunday. "And where we're at right now, obviously using Chase (Anderson) for four innings two days ago and then Zack (Kelly) for three innings (Saturday), we're kind of short in that aspect."