Announcing his candidacy in the centre of the capital on Friday, Janković said he was proud of past achievements that he said placed Ljubljana "among the best in the world."
Best known for closing the city centre for traffic and turning Ljubljana into one of the top tourism destinations in the country, Janković indicated the focus of his next term would be infrastructure and housing.
His plan involves the construction of 1,500 new non-profit flats, a huge number in a city that is chronically short of affordable housing and more than have been built in decades.
As of the end of 2017, Ljubljana had fewer than 3,800 city-owned non-profit flats in total.
Janković also mentioned the renovation of 20% of all roads in the city, three schools, and several community health centres.
In the last election in 2014, Janković won outright in the first round but lost his majority in the city council.
It remains unclear whom he will face this year, as major parties have not yet presented their candidates, even though the vote is just two months away, on 18 November.