Alliance's Michael Long is set to "make history" at Belfast City Hall as he will be installed as Lord Mayor for just three weeks.
It will be the shortest term of office for a mayor in the city, and will also make history as the first time the spouse of a previous Lord Mayor has held the post.
Mr Long's wife, Alliance Party leader, Naomi, was mayor in 2009.
Read more: Every person elected to the NI Assembly and their constituency
The reason for his three-week stint in the position is that he will be replacing his Alliance colleague, Kate Nicholl, whose term of office ends on June 1.
Ms Nicholl was elected last week to the Northern Ireland Assembly to represent South Belfast, and under the dual-mandate rules, must give up her seat on the council as a result.
Mr Long is a former high sheriff of the city, and his installation as Lord Mayor is expected to take place at Monday's monthly meeting of the council at City Hall.
Five other councillors were also elected and will now leave their places in City Hall - Danny Baker of Sinn Féin, the DUP's Brian Kingston and David Brooks, and Nuala McAllister and Peter McReynolds from Alliance.
Three of them - Mr Baker, Mr Kingston and Ms McAllister - are all former mayors.
Read more: Analysis: Voters sent MLAs one clear message.. make Stormont work
Read more: Secretary of State to meet with Stormont parties to press return to government
For the latest politics news straight to your inbox, sign up to our newsletter here.
