[1] He extended his contract with the club on 24 March 2018, keeping him a part of De Kongeblå until 2021.
At the age of 17, Simonsen made his first team debut for Lyngby in the Danish Superliga on 3 March against Hobro IK.
[2] On 21 January 2020, Simonsen joined Danish second tier club Nykøbing FC on a year-long loan.
[3] On 26 January 2021 it was confirmed, that Simonsen had signed a three-year deal with Danish 1st Division club HB Køge.
[4] In August 2016, Simonsen received a call-up for the Denmark under-18 team without making an appearance.