On January 17, 2014, Vanderbilt hired Mason as its new head football coach, succeeding James Franklin. With the hire, Vanderbilt is the first and only school in the Southeastern Conference to have multiple minority head football coaches in its history. After back–to–back home losses, Mason won his first game as head coach against UMass by a score of 34–31. Vanderbilt had been outscored 10–78 in the two games prior to the win. The Commodores struggled offensively for much of the season. Vanderbilt did not score an offensive TD for nine quarters and was the last D1 team to reach the end zone on offense. After a disappointing first season in Nashville, Mason fired both his offensive and defensive coordinators. He hired Andy Ludwig, formerly the offensive coordinator at Wisconsin, to run the offense. Mason decided to call the defensive plays himself. His second season saw moderate growth for Vanderbilt, culminating in a 4–8 record with numerous firsts for the young head coach. Mason earned his first win against an SEC opponent and his first win while on the road. The team was praised for a nationally respected defensive scheme, but the Commodores were unable to perform equally well with their offensive or special team capabilities. Mason continued his role as Head Coach and Defensive Coordinator in his third season at Vanderbilt, leading the Commodores to a 6–6 record in 2016, earning bowl eligibility for the first time as a head coach. Mason won his first SEC road game on October 15 at Georgia, by the final score of 17–16. The Commodores nearly picked up another road win against a ranked conference opponent on November 5 at Auburn, losing 23–16 after throwing a late interception at the opponents' 30 yard line in the final minute. After a disappointing loss to Missouri the next week, the Commodores needed to beat both Ole Miss and Tennessee at home in the team's final two games of the season to assure themselves of bowl eligibility, though they would have still reached a bowl with a 5–7 record based on a high Academic Performance Rating, which determines the bowl eligibility of five win teams for open bowl slots. APR became a non-factor as the Commodores upset both Ole Miss and Tennessee at home in back-to-back games to end the regular season with a 6–6 record on the strength of 3 conference wins. Vandy scored a combined 83 points in the two wins as the offense came alive late in the season. Mason's dancing on the sideline and post-game celebration after defeating Tennessee were widely shared on Twitter and ESPN. Under Mason, redshirt junior linebacker Zach Cunningham became a national finalist for the Butkus Award, given to the nation's best collegiate linebacker. Year four for Mason was a disappointing regression. Despite an historic 3–0 start, including defeating a then 18th ranked Kansas State at home in week 3 and ending a five year losing streak of opening games since 2012, the Commodores finished 5–7 and were unable to play in a bowl game despite APR. Derek Mason was unable to answer the Alabama Crimson Tide in week 4, and experienced a five game losing streak until hosting Western Kentucky in week 10. However, despite their lackluster performance, Vanderbilt was able to defeat the University of Tennessee, ensuring the Volunteers first ever 8 loss season. The 2018 season began with Mason considered on the hot seat, one of 10 coaches identified by ESPN to be facing this challenge. He is the first Vanderbilt football coach to beat the Tennessee Volunteers three years in a row since Dan McGugin did it in 1926, 1925, and 1924.
Personal life
Mason and his wife, LeighAnne, have two daughters, Sydney and Makenzie. Makenzie is a lacrosse player for the University of Florida.
