Haslett began his NFL coaching career as a linebackers coach for the Los Angeles Raiders in 1993. Haslett next coached linebackers for the New Orleans Saints in 1995 and was promoted to defensive coordinator for the 1996 season. Haslett then coordinated the Pittsburgh Steelers defense for the 1997 through 1999 seasons.
In 2005, Haslett's sixth season with the Saints, the team stumbled to a 3–13 record. The season was marred by Hurricane Katrina's devastation of New Orleans. This forced the franchise to temporarily relocate their operations to San Antonio, playing three of their 'home' games in the Alamodome. Another four home games were played in Baton Rouge at LSU's Tiger Stadium, and one took place at Giants Stadium in New Jersey (against the New York Giants). Haslett was fired after the close of the 2005 season.
Haslett became the St. Louis Rams' defensive coordinator to start the 2006 season. On September 29, 2008 Haslett was named the interim head coach of the Rams after Scott Linehan was fired. The Rams gave Haslett an interim coach's contract, containing a clause that promised him the permanent head coach's job if the team won at least six games that season. Within a few weeks, this clause was nullified by the NFL, because it violated the league's "Rooney Rule". He won his first game as interim head coach of the Rams with a 19-17 victory over the 4-1 Washington Redskins. That win was followed by a 34-14 drubbing of the Dallas Cowboys on 19 October 2008. This brought the Rams to a 2-4 record. The team would lose their final 10 games, leaving Haslett with an interim record of 2-10 on the year. On January 15, 2009 the Rams announced that Haslett was no longer in consideration for the permanent head coaching position and that the team would be going in a "new direction".
Haslett was hired as the Washington Redskins defensive coordinator on January 12, 2010 under head coach Mike Shanahan. Haslett replaced the retiring Greg Blache. After many speculated he would be fired after the disastrous 2013 season, new head coach Jay Gruden announced Haslett would remain on the team for the upcoming 2014 season. On December 31, 2014, the Redskins announced that Haslett would leave the Redskins by mutual agreement.
Jay Gruden, Washington Redskins (2014-) Gruden served as offensive coordinator under Haslett in the UFL's Florida Tusker's 2009 season. Haslett later served as defensive coordinator under Gruden in the NFL's Washington Redskin's 2014 season (see above).
Former Assistant Coaches that became NCAA Head Coaches: