In the runoff held on Sunday, Catovic won slightly over 52 per cent of the votes, while her rival, Branko Ivanovic of the Socialist People's Party (SNP) gained less than 47 per cent.
The early local elections in Kotor were triggered by a rift in the ruling four-party coalition following a scandal surrounding the sale of 500,000 square metres of land in the town's district of Grblje.
The first round of voting took place two weeks ago. The Croat Civil Initiative (HGI) was the first Croat party to take part in elections in 66 years, capturing two seats in the local assembly. The party did not have its mayoral candidate and called on its members to vote for Catovic.