Mouritsen joined FC Nordsjælland in 2012, where he played 2 years on the youth teams.
He was permanently moved to the first team squad in the summer 2014, at the age of 19.
He got his Danish Superliga debut against Hobro IK on 28 February 2015, where he played the whole match.
[3][4] On the last day of the summer transfer market, Mouritsen got his contract with FCN terminated, and joined FC Roskilde.
[12] After only three months at Skive, Mouritsen joined fellow league club FC Helsingør on 28 January 2021.