Before the start of the 2015–16 season, Allen suffered an injury during one of the pre-season matches and was ruled out for a month. On 13 January 2016, he scored a last-minute equalizer in a 3–3 home draw against league leaders Arsenal. Thirteen days later, he scored the winning penalty in a shootout against Stoke City to send Liverpool to the 2016 League Cup Final. Allen was an unused substitute for Liverpool as they lost the final on penalties to Manchester City. However, Allen did play in the 2016 UEFA Europa League Final against Sevilla on 18 May 2016 in Basel, where despite initially taking the lead, Liverpool were defeated 3–1. At the end of the season, Allen expressed his desire to play regular football.