On August 14, 2016, Allen started his professional career with the Hungarian team EGIS Körmend, signing a one-year deal.[2] On November 8, 2016, Allen recorded a career-high 37 points, shooting 15-of-23 from the field, along with seven rebounds and two assists in a 92–75 win over Limburg United. He was subsequently named FIBA Europe Cup round 4 Top Performer.[3]
On June 16, 2017, Allen signed a one-year deal with the French team BCM Gravelines-Dunkerque.[4] On July 1, 2017, Allen joined the Utah Jazz for the 2017 NBA Summer League.[5] On October 21, 2017, Allen recorded a season-high 32 points, shooting 13-of-17 from the field, along with four rebounds in a 75–74 win over Élan Chalon.[6]
Ironi Nahariya (2018–2019)
On July 9, 2018, Allen signed with the Israeli team Ironi Nahariya for the 2018–19 season.[7] On February 28, 2019, Allen recorded a season-high 25 points, shooting 11-of-17 from the field, in a 75–93 loss to Hapoel Eilat.[8] In 33 games played for Nahariya, he averaged 11.9 points, 5.4 rebounds and 2.1 assists per game.
Göttingen (2019–2020)
On July 29, 2019, Allen signed a one-year deal with the German team BG Göttingen.[9] He averaged 10.7 points, 3.7 rebounds and 1.3 assists per game and was voted to Eurobasket.com All-German Bundesliga Honorable Mention.[10]
Hamburg Towers (2020–2021)
On August 15, 2020, Allen signed with the German team Hamburg Towers.[10]
Medi Bayreuth (2021–2022)
On July 15, 2021, Allen signed a one-year deal with the German team Medi Bayreuth.[11]