As a Cowboy, Johnston played in 149 consecutive games from 1989-1997. He also became one of the greatest special teams players in franchise history. He scored 22 career touchdowns and had more receptions than carries. His 294 receptions is the third highest number among Cowboys running backs, totaling 2,227 yards for a 7.6 yards average, compared to 232 carries for 753 yards for a 3.2 yards average. In 1993 Johnston had 50 receptions and averaged 7.4 yards per catch. Due mainly to Johnston's contributions, the NFL created the fullback position in the Pro Bowl. Prior to this change, blocking fullbacks had little chance of beating out traditional running backs, who had better statistics. In 1993 Johnston became the first fullback ever selected for the Pro Bowl, earning trips in 1993 and in 1994. He was also a 3 time Super Bowl champion.

This Dallas Cowboys jersey was signed in silver by Johnston and was inscribed "Moose," "America's Team," and "3 x SB Champ." This jersey includes a JSA sticker and COA.