Hearns had an amateur boxing record of 155 wins and 8 losses and won the 1977 National Golden Gloves Light Welterweight Championship. That same year, he turned professional and in 1980 won the WBA World Welterweight Championship.
In 1982, he moved up in weight and won the WBC Super Welterweight Championship. Hearns won the Ring Magazine Fighter of the Year Award in 1980 and 1984. In 1987, he again moved up in weight and won the WBC Light Heavyweight Championship.
Later in his career, Hearns also won two Cruiserweight Championships. Hearns retired with a record of 61 wins, 5 losses, and 1 draw.