Janković was elected to the Sremska Mitrovica municipal assembly in the 2012 Serbian local elections on the electoral list of the Progressive Party[2] and was subsequently chosen as the municipality's deputy mayor.[3] He was elected again in the 2016 local elections[4] and served as president (i.e., speaker) of the assembly for the next four years. He did not seek re-election at the local level in 2020.
Janković received the seventy-third position on the Progressive Party's Aleksandar Vučić — For Our Children coalition list in the 2020 Serbian parliamentary election[5] and was elected when the list won a landslide majority with 188 mandates. He is a member of the assembly's environmental protection committee, a deputy member of the defence and internal affairs committee and the committee on the rights of the child, the head of Serbia's parliamentary friendship group with Laos, and a member of the parliamentary friendship groups with China, Russia, and Slovenia.[6]