Miles is nicknamed "the Hat" for his signature white cap, as well as "the Mad Hatter" for his eccentricities and play-calling habits.

Miles led the 2007 LSU Tigers football team to a win in the BCS National Championship Game, defeating Ohio State.

[3] He earned all-state honors as a lineman in football[4] as well as letters in baseball and wrestling at Elyria High School in Ohio, graduating in 1972.

[5][6] He attended the University of Michigan from 1972 to 1975, playing for the football team under head coach Bo Schembechler, earning letters in 1974 and 1975.

Miles then accepted a promotion to offensive coordinator on former Colorado assistant Bob Simmons's staff at Oklahoma State.

[citation needed] On January 2, 2005, Miles was named as the 32nd head football coach of Louisiana State University (LSU).

[24] In August 2005, days before Miles was to make his debut as the coach of LSU, Hurricane Katrina struck southern Louisiana.

[25] The Tigers second game, which was against Arizona State, was moved from Baton Rouge to Tempe because the LSU campus was still serving as an emergency center for Hurricane Katrina relief.

However, the Tigers were ranked ahead of Arkansas at the end of the regular season, and were rewarded with an invitation to face Notre Dame in the Sugar Bowl, where they defeated the Irish by a score of 41–14.

Coincidentally, the 2007 regular season also ended with a loss to Arkansas in a game marked by several of Miles' hallmark unconventional calls.

On the day of the game, Kirk Herbstreit wrongly reported on ESPN's College GameDay that Les Miles had accepted an offer to succeed Lloyd Carr as the head coach at Michigan.

On the day of the SEC championship game, Kirk Herbstreit incorrectly reported on ESPN's College GameDay that Miles had accepted an offer to succeed Lloyd Carr as the head coach at the University of Michigan.

[37] Miles cleared up any confusion himself in a last minute press conference to reporters saying, "There was some misinformation on ESPN and I think it's imperative that I straighten it out.

"[38] The speculation resurfaced two weeks later when The Detroit Free Press reported that Michigan athletic director Bill Martin and university president Mary Sue Coleman spoke with Miles directly over the phone a few days after he signed a contract extension with LSU.

[39] In response to the report, Miles issued a statement acknowledging the conversation, but claimed that he was merely offering advice and assistance to Martin on Michigan's search and that he is not a candidate for the vacancy.

The Tigers went 13–0, including a hard-fought 9–6 overtime duel with Alabama in a Game of the Century, and won the SEC Championship over Georgia.

[57] On September 25, 2016, LSU fired Miles and offensive coordinator Cam Cameron after an 18–13 loss to Auburn the previous day and a 2–2 start to begin the season.

[65][66] Miles was placed on administrative leave on March 5, 2021, due to an investigation of inappropriate conduct with female students while at LSU.

[68] USA Today's Dan Wolken wrote that the decision to place Miles on administrative leave was "merely a placeholder" until lawyers could decide whether his ouster would be deemed a mutual agreement to part ways or a firing.

At a press conference the following day, Long said that Miles had assured him that there was nothing in his past "that could potentially embarrass the university or himself or our program."

Long added that in February, he and other school officials had been alerted about "a legal dispute in Louisiana," but Miles had again assured him there was nothing to worry about.

The article also alleges Miles suggested the players settle their dispute "on the practice field, pitting them against each other—head-on—in full-contact drills.

The series alleged Oklahoma State used a bonus system for players, orchestrated by then-assistant coach Joe DeForest, along with direct payments and no-show or sham jobs involving boosters.

[76] In 2013, LSU requested that the law firm Taylor Porter conduct an investigation into Miles's relationships with female students after a number of accusations.

[77] On June 22, 2023, the National Collegiate Athletic Association (NCAA) announced that LSU would vacate 37 wins during Miles' tenure, from 2012 to 2015, as punishment stemming from a scandal involving former All-SEC offensive lineman Vadal Alexander.

[78] As a result of the vacated wins, Miles' career head coaching record was reduced from 145–73 (.665) to 108–73 (.597), which dropped him below the .600 threshold of eligibility for the College Football Hall of Fame.