Getting his football education in the youth ranks of local team Esbjerg fB, he saw limited first team opportunities, and in the summer of 2010 he decided to join Vejle Boldklub in the Danish 1st Division. After two successful seasons for Vejle, both of them in the Danish 1st division, bigger teams started to pay him attention. In March 2012 he was sold to Norwegian club Rosenborg BK. He became a regular 1st team starter for the Norwegian side, but after only 18 games he had yet to settle personally. In the same summer he was sold back to his childhood club Esbjerg fB on a 4-year contract. During his second stay at Esbjerg, alongside twin brother Jakob Ankersen, played an integral part of the Esbjerg team that following promotion won the Danish Cup and finished 4th in the Danish Superliga. During a 5–1 win over AGF Aarhus on 10 August 2013, Ankersen scored a sensational goal reminiscent of Marco van Basten's strike in the final of Euro 88. The goal was shortlisted for the 2013 FIFA Puskás Award. In January 2014 he was signed by RB Salzburg after impressing a against them in the group stages of the Europa league, and was praised for his ability to play on either defensive flank. He joined F.C. Copenhagen in the summer of 2015 initially on loan, before signing permanently the season after. He was linked with a move to the Premier League club Newcastle United. Ankersen was nominated for the goal of the season by the Danish football federation in 2017. On transfer deadline day, 2 September 2019, Ankersen joined Italian Serie A club Genoa on a contract until June 2021 with an option for a further year.
International career
Ankersen has never represented any of the Danish national youth teams. On 17 May 2013 he was called up for the Danish National Team for a friendly against Georgia. In the match, he remained an unused sub for the entire game. On 14 August 2013, he made his international debut in a 3–2 loss to Poland, coming on as a substitute for Nicolai Boilesen at half-time. Ankersen scored his first goal ever in Danish national team colours on 11 November 2016 in a 2018 FIFA World Cup Qualification match against Kazakhstan. Denmark won 4-1. In May 2018 Ankersen was named in Denmark’s preliminary 35-man squad for the 2018 World Cup in Russia. However, he did not make the final 23.
