[1] Lynch was signed as an undrafted free agent by the Dallas Cowboys after the 1987 NFL draft in April.
[6] He was active for 11 regular-season games and both playoff contests as a backup defensive back.
In 1989, he appeared in all 16 games with 2 starts, registering 38 tackles, 3 interceptions and 8 passes defensed.
He had 2 interceptions, including one returned for his first career touchdown, in the thirteenth game against the Philadelphia Eagles.
In the pregame show for the NFL Network's presentation of Thursday Night Football on September 20, 2012, former Cowboys receiver Michael Irvin recalled a game he played against Lynch (then playing for the Phoenix Cardinals) 20 years earlier on September 20, 1992.
In 1993, he appeared in 16 games with 15 starts (10 at safety and 5 at cornerback), while leading the team in total plays with 925 out of 968 defensive snaps.
In the season opener against the Philadelphia Eagles, he had 10 tackles and one forced fumble, which he returned 55 yards for a touchdown.
He started at cornerback against the Pittsburgh Steelers, making 7 tackles and one forced fumble in a 20–17 overtime win.
He set an NFL record for longest interception return in overtime (72 yards) against the Seattle Seahawks.
He made 6 tackles, one interception and 2 passes defensed against the New York Jets on October 6.
Lynch as a high school student, sold hot dogs and peanuts at Oakland Coliseum stadium during Raiders games.
His nephew Marshawn Lynch was a running back who compiled more than 10,000 yards rushing for the Buffalo Bills, Seattle Seahawks, and Oakland Raiders.