Sale, a two-time All-Star, went on the disabled list on April 22 with a left flexor strain and tossed a successful bullpen session before the team's 7-6 victory over the Kansas City Royals on Tuesday.
The left-hander last pitched April 17 against the Boston Red Sox, throwing seven innings of one-hit ball and striking out 10.
"He threw free and easy," White Sox manager Robin Ventura said. "It's another step in the right direction. We'll continue to see how he is."
Sale is 3-0 with a 2.30 ERA and 0.84 WHIP in four starts this season for the White Sox, who are 23-24 and in third place in the American League Central. MLB Power Rankings: White Sox No. 21 in this week's MLB Power Rankings