A former RUC officer and Orangeman is to become a Sinn Fein MLA replacing retiring Assemblyman Francie Brolly.
Coleraine councillor Billy Leonard was picked over Limavady councillor Brenda Chivers to succeed Mr Brolly for the constituency of East Londonderry at a party meeting last night.
The co-option will take effect early in the new year.
Mr Brolly was elected to the Assembly in 2003.
He announced that he planned to retire last month.
Mr Leonard said it was “an honour” to step into Mr Brolly’s shoes.
“I intend to carry on the work that Francie Brolly has been involved in and to represent all the people of this constituency,” he said.
“The north-west region is one of the most deprived areas on this island and it is important that we have strong leadership to ensure East Derry is given its fair share.”