Born in New Orleans, Mullins won two state championships and was the 2008 Louisiana Gatorade Player of the Year while at Jesuit High School.
He played collegiately at Maryland, where he was a two-time All-American and helped the Terrapins to back-to-back appearances in the College Cup.
In a 2017 game against San Jose Earthquakes, Mullins became the first player in MLS history to score four goals in a single half.
Mullins scored one goal with the Crew in parts of two years before another trade brought him across the border to Toronto FC, where he played the final seasons of his career.
Mullins scored his final goal in April 2021, during a 2021 CONCACAF Champions League match against León, and retired from professional soccer at the end of the 2021 season.
Including his time with semi-professional clubs Baton Rouge Capitals and New Orleans Jesters early in his career, Mullins played more than 200 senior games.
He and his family lost their home after Hurricane Katrina hit the city in 2005, forcing them to take refuge in Brookhaven, Mississippi and Baton Rouge, Louisiana.
[8] Mullins finished the season with five goals from 21 appearances and was named as the Atlantic Coast Conference Men's Soccer Freshman of the Year.
[17] Despite rumors that he would sign a Generation Adidas contract and enter the 2013 MLS SuperDraft, Mullins decided to stay at Maryland for his senior season.
[1] On January 10, 2014, Mullins won his second consecutive Hermann Trophy, making him the fourth male in NCAA history to win the award in back-to-back seasons.
[1] Following his freshman season at Maryland, Mullins returned to the PDL and to his home state of Louisiana by joining New Orleans Jesters.
[29] Mullins found success against the Texas-based clubs in the Mid South Division, with his tally including goals that June against Texas Dutch Lions and Austin Aztex.
[33] Mullins added a goal against Knoxville Force in late June, ending his three seasons in New Orleans as one of the leading scorers in Jesters history.
Seven minutes after coming on, he provided an assist on the match-tying goal by Chris Tierney, although the Revolution would go on to lose 2–1 after extra time.
[43] He found the back of the net five more times during the regular season, including the final goal of a 4–4 draw with Toronto FC on July 12.
[41] Following the 2015 season, Mullins was one of 10 New York City FC players who had their contract options exercised by the club, sealing his return to the Bronx for a second campaign.
[41] Mullins was traded to D.C. United on July 20, 2016, in exchange for general and targeted allocation money and an international roster slot.
[46] Three days after the trade, he made his debut for the capital club, coming on as a 58th-minute substitute in a 4–1 defeat against Toronto FC.
[41] That tally included his first career hat trick, part of a 6–2 victory over Chicago Fire on August 27.
[51] He missed more than a month at the start of the year due to a pulled hamstring, underwent surgery for a torn meniscus in early June, and didn't return to full fitness until mid-August.
[55] He made his debut for the club ten days later, playing 22 minutes off the bench in Crew SC's 3–2 victory over Orlando City.
[41] Exactly one year after being acquired by the Crew, Mullins was traded to Toronto FC in exchange for forward Jordan Hamilton, $50,000 in targeted allocation money, and a 2019 International Roster Spot.
[67] He finished the year with two goals and one assist from 18 appearances in all competitions, helping Toronto qualify for the MLS Cup Playoffs and the 2020 Canadian Championship final.
[63][68] After a difficult 2021 season, where he failed to score a single goal in league play, Mullins had his contract option declined by Toronto.