After a standout career at Morehead State University, Simms was drafted in the first round by the New York Giants with the number seven selection overall in the 1979 NFL Draft. Simms played his entire professional career with the Giants and was named Most Valuable Player (MVP) of Super Bowl XXI, after he led the Giants to a 39–20 victory over the Denver Broncos and set the record for highest completion percentage in a super bowl, going 22 for 25. He also was named to the Pro Bowl for his performances in the 1985 and 1993 seasons.

He finished his career with 33,462 passing yards and has since gone on to a career broadcaster of NFL games—first as an analyst for ESPN, then as a in-game color commentator with NBC, and also with CBS. His number 11 is retired by the New York Giants.