From USC, Dennis Smith was drafted 15th overall in the 1981 NFL Draft and was a decorated consensus All-American who immediately injected raw physicality into the secondary. Transitioning into the starting strong safety spot early in his career, Smith established himself as an intimidating secondary enforcer—setting the blueprint for a generation of box safeties who could crush ball-carriers in run support while holding their own in pass coverage.

Smith’s breakout arrival occurred during his third season in 1983, when he achieved a career-best total of 114 tackles, along with five sacks and four interceptions. This remarkable performance initiated a decade-long period of leadership in the secondary. Acting as the formidable enforcer of Denver’s defense, Smith exceeded 100 tackles in five distinct seasons—culminating with a career-high of 120 tackles in 1992—while consistently leading the team's defensive backs in tackles and forced fumbles.

During the late 1980s and early 1990s, his play reached elite level. Smith earned six Pro Bowl selections (1985, 1986, 1989–1991, 1993) and two All-Pro honors. As the veteran starter alongside a young Steve Atwater from 1989, they created one of the most formidable safety duos in NFL history. That defensive backfield was crucial for Dan Reeves' teams, driving Denver to the AFC playoffs and securing three Super Bowl appearances in XXI, XXII, and XXIV.

Smith was not only known for his punishing hits but also for his exceptional ball skills and field awareness. Over his 14-year career with Denver, he amassed 30 interceptions—one of which he returned for a touchdown—along with 17 fumble recoveries and 15 sacks. His versatile skill set consistently disrupted opposing offenses, and he was regarded as a revered team leader until he retired after the 1994 season.

In his 14-year career, Smith had 1,171 total tackles, 30 interceptions, 15 sacks, and 17 fumble recoveries.  In 2001, he was enshrined in the Broncos Ring of Fame.