Pie was batting .362 at Iowa with nine home runs and 43 RBIs. This is his third call-up to the big leagues. He was optioned to Iowa on July 13, and batted .307 in July at Iowa with six homers and 12 RBIs. This month, he was hitting .455 (10-for-22) with six RBIs.
The highly-touted outfielder could play either corner or center field for the Cubs. In his two previous stints with the Cubs, Pie hit .216 in 48 games with two homers and 18 RBIs.
An official announcement was expected later Wednesday.
The team has made a roster move a day the past three days, beginning Monday when they added Eric Patterson to take injured Alfonso Soriano's spot on the roster. On Tuesday, Will Ohman was optioned to Iowa and right-hander Sean Gallagher called up.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.