In 1981 he was wealthy enough to purchase the White Sox for $19 million. The purchase was brokered by American National Bank who arranged for a limited partnership. He followed previous eccentric White Sox owners Charles Comiskey, who was known as a miser, and Veeck, who was known as a prankster who gutted the team by trading away promising prospects. Soon after buying the White Sox, he signed Greg Luzinski and Carlton Fisk. He also tripled the team promotional budget and increased the number of team scouts from 12 to 20. By the 1983 Major League Baseball season the White Sox made the playoffs with the best record in the Major Leagues. The team initially signed a television deal with the newly founded Sportsvision under the new leadership of Chairman Reinsdorf and Vice Chairman Eddie Einhorn, but that arrangement quickly fizzled. Einhorn continued as Vice Chairman of the White Sox until his death in 2016.
After Reinsdorf purchased the team in 1981, the White Sox experienced erosion of fan and media support. He complained about old Comiskey Park with its foibles such as numerous obstructed view seats and threatened to move the White Sox. Among his threats was moving the team to Itasca or Addison, Illinois in DuPage County. Reinsdorf, through his real estate business, purchased 100 acres (400,000 m) in Addison. Chicago Mayor Harold Washington lobbied the Illinois legislature, and subsequently then-Illinois Governor James R. Thompson promoted a package of incentives to retain the team in Chicago. The state floated bonds to build New Comiskey Park and let Reinsdorf keep all parking and concession revenues, as well as the $5 million per year from 89 skyboxes. Reinsdorf and Chicago Blackhawks owner William Wirtz contributed $175 million to fund the construction of the largest arena in the United States. When the United Center opened in 1994 all of the skyboxes were leased for up to eight years. As per the collective bargaining agreement, Reinsdorf was allowed to exclude 60% of luxury suite revenue from "basketball-related income" and thus it is not part of the revenue sharing income.