Lyght was a first-round pick, fifth overall, of the Los Angeles Rams in the 1991 NFL Draft. He was the second cornerback drafted, following third overall pick Bruce Pickens. On August 16, 1991, after a training camp holdout, Lyght signed a five-year $5.6 million deal that made him the second-highest paid player on the Rams. As a rookie in 1991, Lyght started the last eight games of the season at left cornerback after battling several early-season injuries. In 1992, he missed four games after dislocating his shoulder versus Miami On September 20. He was named the NFC Defensive Player of Week after posting nine tackles and two interceptions against the New England Patriots on September 13. In 1993, Lyght tied for team lead with two interceptions but suffered a knee injury in pregame drills on November 21 and was subsequently placed on injured reserve.