Werner first became a part owner of the San Diego Padres in 1990, later was part of a group that purchased the Boston Red Sox, and has served as chairman of the Red Sox since February 27, 2002. Since then, the team has won four World Series—the 2004 title ending an 86-year championship drought—and qualified for the postseason 10 times. In 2018, the Red Sox won a franchise-record 108 games and went on to win a ninth World Series title. Werner became chairman of Liverpool Football Club in 2010. In his time in office, Liverpool has won four trophies including the UEFA Champions League in 2019 and the Premier League in 2020 under manager Jürgen Klopp.