Anne Donnelly has been selected by the SDLP to replace Pat Ramsey on Derry City Council.
Mr Ramsey, who is also an MLA for Foyle, stepped down from the council earlier this week in alignment with party policy to end dual mandates.
Ms Donnelly said she was "honoured" to represent the people of the Bogside, Creggan and Brandywell.
"I am committed to providing strong and responsible leadership and decision making for all," she said.
"I have worked all my life to promote the interest of workers, of women and of disadvantaged people and communities here in Ireland and elsewhere.
"I will continue that work as an SDLP representative on Derry City Council."