The Cowboys took a flyer on Walker, hoping he would leave the USFL for the NFL. Dallas drafted Walker with the number 114 pick in the 1985 NFL draft. Walker would join the Cowboys in 1986, splitting the backfield with number 33.
In that first season with Dallas, Walker ripped off the longest run in the league for the season, with an 84-yard scamper.
Not only was Herschel a force running the ball, averaging 4.9 yards-per-carry with 12 touchdowns, but he was also an asset in catching the ball out of the backfield for Dallas. Walker caught a hefty 76 passes for 837 yards and two touchdowns in his first season as a Cowboy.
1987 would be a Pro Bowl season for Walker with Dallas. He had the best number of yards from scrimmage in the league with 1,606. In just twelve games for Dallas, he ran for 891 yards and caught 60 passes for 715 yards.
From a numbers perspective, 1988 would be Walker's best year with Dallas. Playing and starting in a full 16 game season, Herschel ran for an impressive 1,514 yards, while catching the ball 53 times for 505 yards. His total number of yards from scrimmage was 2,019.
With Walker dominating out of the backfield, and after playing in a small number of games for Dallas in the 1989 NFL season, the Cowboys traded Herschel to the Minnesota Vikings in what was a blockbuster deal.
The trade was huge for Dallas, as they received five players, six draft picks and potential draft picks based on whether one of the five players they got in the trade were cut. Some of the picks that wound up coming to the Cowboys would be used to select Emmitt Smith, Russell Maryland, Kevin Smith and Darren Woodson.
After playing for Minnesota, the Philadelphia Eagles and the New York Giants, Walker would return to the Dallas Cowboys and once again wear his trademark number 34. Walker primarily returned kicks for Dallas in 1996 and 1997. He wound up his career in the NFL, with the Cowboys, returning 50 kicks for 1,167 yards.