Kane beat Toronto Maple Leafs center Auston Matthews, Tampa Bay Lightning goaltender Andrei Vasilevskiy and Edmonton Oilers center Connor McDavid.
The right wing scored a milestone 400th goal in a rivalry win against the Detroit Red Wings in February. Kane finished the 2020-21 season with 15 goals, 51 assists and 66 points.
Jonathan Toews, who announced his plans of returning next season with the Hawks, won the same ESPY award in 2015.
Kane was nominated for the ESPY back-to-back in 2016 and 2017.
The 32-year-old has won three Stanley Cups with the Chicago Blackhawks in 2010, 2013 and 2015 and also won the Conn Smythe Trophy in 2013 as the most valuable player of the playoffs. Kane also won the Hart Memorial Trophy as Most Valuable Player and Art Ross Trophy as scoring champion in the 2015-16 season.