He became a municipal councilor for the PVV in Zandvoort in 2015. Since 2018 he has also sat on the Provincial Council of North Holland where he acts as the party's group leader. He also sits on the council's committee for social mobility and finance. In the 2023 Dutch general election, Deen was elected to the House of Representatives.[2][3][4] He serves as his party's spokesperson for emancipation.[5] When Femke Halsema, mayor of Amsterdam, allowed a pro-Palestinian protest on the first anniversary of the Hamas-led attack on Israel of 7 October 2023, PVV leader Geert Wilders criticized her, after which Deen requested Minister of the Interior and Kingdom Relations Judith Uitermark to dismiss Halsema. Prime Minister Dick Schoof responded that it was unacceptable to request in parliament the firing of a mayor for political reasons.[6] During the same debate, Deen filed an amendment to freeze King Willem-Alexander's income in the 2025 budget.[7]