Smith was selected by the Dallas Cowboys in the 1st round (25th overall) of the 1971 NFL Draft, after dropping because of an ankle injury he suffered in college. This injury limited him to only 7 games during his rookie year. He spent the first seven games of the season on the team's taxi squad, but when he joined the regular roster, he showed the Cowboys he had a future in the NFL and even contributed in the Cowboys win in Super Bowl VI.