Larsen ran for parliament in the 2015 Danish general election, though was not elected. He received 3,449 personal votes, which made him the Social Democrats' primary substitute in the East Jutland constituency. He entered parliament as a substitute member four times during the 2015–2019 term. These periods were from 12 November 2015 to 18 March 2016 (substituting for Kirsten Brosbøl), from 19 March 2016 to 30 June 2017 (substituting for Maja Panduro), from 3 October 2017 to 30 November 2017 (substituting for Jens Joel) and from 15 January 2019 to 7 May 2019 (substituting for Maja Panduro). Larsen ran again in the 2019 election, where he was elected into parliament on his own mandate, receiving 5,708 votes.[2][3]