Matejić appeared in the twenty-fifth position on the Progressive Party's electoral list for the Kovačica municipal assembly in the 2016 Serbian local elections.[3] The list won twenty-one mandates.[4] He was not returned and does not appear to have received a mandate as a replacement delegate over the next four years.
He was given the 176th position on the party's Aleksandar Vučić — For Our Children list in the 2020 Serbian parliamentary election and was elected when the list won a landslide majority with 188 mandates.[5] He is a member of the assembly committee on constitutional and legislative issues; a deputy member of the European integration committee and the agriculture, forestry, and water management committee; and a member of Serbia's delegation to the Inter-Parliamentary Union.[6]