He recently served as the assistant head coach for the Las Vegas Raiders of the National Football League (NFL).

Lewis's head coaching tenure oversaw improved fortunes for the struggling Bengals and helped transform the team into postseason contenders.

The newly relocated Baltimore Ravens (formerly the Cleveland Browns), hired Lewis as their defensive coordinator in 1996, a position that he held for six seasons (1996–2001).

General manager Rich McKay was ready to formally offer the job to Lewis, and the Ravens actually held a going-away party for him.

However, the team's owners, the Glazer family, were unwilling to give the job to another defense-minded coach after firing Tony Dungy.

[9] Lewis was also a prime candidate for the Buffalo Bills coaching vacancy, but was passed over in favor of Tennessee Titans defensive coordinator Gregg Williams.

Shortly afterward, Lewis was hired by the Washington Redskins as defensive coordinator and assistant head coach under Steve Spurrier.

This included wins in all six games against their AFC North opponents, marking the first time in franchise history they accomplished this feat.

[13] The Bengals finished the season 10–6, winning the AFC North title and earning only their second trip to the playoffs in 19 years.

The team lost three of their most productive players from the 2010 season, receivers Terrell Owens and Chad Ochocinco along with defensive back Johnathan Joseph, while quarterback Carson Palmer, the team's starter since 2004, refused to play for the Bengals moving forward, leading to him being traded midway through the season.

It was the first time the Bengals had won five consecutive games since 1988, when the team advanced to Super Bowl XXIII with Wyche as their coach.

They finished the season 9–7 and made the playoffs as the #6 seed, where the Bengals lost to the Houston Texans in the wild card round.

Cincinnati started 2012 with a 44–13 loss to the eventual Super Bowl XLVII champion Baltimore Ravens, the most lopsided opening day defeat in franchise history.

However, the team was eliminated in a first-round wild card game for the fifth straight year, this time against their divisional rivals, the Pittsburgh Steelers.

Leading 16–15 near the end of the fourth quarter, Lewis faced criticism for not keeping his players under control after penalties drawn by Vontaze Burfict and Adam Jones moved the Steelers into field goal range and allowed them to make a game-winning kick with eighteen seconds remaining.

The losing seasons, combined with Lewis' winless playoff record and previous five consecutive first-round eliminations led to speculation towards his future in Cincinnati and the potential end of his coaching tenure.

[20] The extension was met with criticism from the media and Bengals fans due to his 0–7 playoff record and only winning 13 out of 32 games in the previous two seasons.

Afflicted by season-ending injuries to several players and a struggling defense that ranked last in yards allowed, the Bengals finished the year with a 6–10 record to place at the bottom of their division.

With a year left on his contract, Lewis and the Bengals announced that they had mutually parted ways following the conclusion of the 2018 season on December 31.

[26] After his departure from the Bengals, Lewis was hired as a game and studio analyst for Turner Sports's coverage of the Alliance of American Football (AAF).