He played as a quarterback in the National Football League (NFL) for the Dallas Cowboys, New Orleans Saints, Chicago Bears, St. Louis Rams, Tampa Bay Buccaneers, and Indianapolis Colts.
As a senior in 1984, he passed for over 2,000 yards and 25 touchdowns, receiving USA Today prep Academic All-America and the Minneapolis-St. Paul Metro football player of the year honors.
In 1988, Walsh finished 4th in the Heisman Trophy balloting and runner-up to the Davey O'Brien Award, after posting 3,115 passing yards, 29 touchdowns and 12 interceptions.
He suffered his only defeat as a starter against the University of Notre Dame, 30–31, after passing for 424 yards (second in school history) and losing a shot at the National Championship.
He left school in April 1989 and declared for the NFL supplemental draft, skipping his final year of eligibility.
[6] The Saints acquired Walsh, because quarterback Bobby Hebert was in the middle of a contract hold out that lasted all season long, and John Fourcade got off to a poor start.
[8] On April 26, 1994, the Chicago Bears signed Walsh as an unrestricted free agent, reuniting with former Cowboys and Hurricanes defensive coordinator Dave Wannstedt.
[16] In December 2008, Walsh accepted the head football coaching job at Cardinal Newman High School in West Palm Beach, Florida.
In April 2015, Walsh accepted the Director of Football position at IMG Academy, replacing Chris Weinke.
[19] In December 2021, Walsh was named the head football coach at his high school alma mater, Cretin-Derham Hall in St. Paul, Minnesota.
[20] After winning a section championship and returning the program to the state tournament for the first time in 7 years, Walsh will no longer lead the Raiders in 2025.
Walsh is the uncle of fellow Cretin-Derham Hall High School alumnus and National Hockey League defenseman Ryan McDonagh, who currently plays for the Tampa Bay Lightning.