The White Sox selected Ellard's contract from Triple-A Charlotte on Tuesday.
Ellard will join the White Sox's bullpen to make up for the loss of Tanner Banks, who was traded to Philadelphia ahead of Tuesday's trade deadline. The left-handed Ellard has put up a 3.76 ERA and 1.34 WHIP through 40.2 innings with Charlotte this season, and he'll be making his MLB debut whenever he gets into a game.