Thrissur Mayor Ajitha Vijayan resigned from the position on Tuesday.
She announced her resignation at a special council meeting and handed over her resignation letter to the Corporation secretary.
Her resignation was part of the prior seat-sharing formula in the LDF.
The CPI(M) will hold both Mayor and Deputy Mayor posts in the last year of the current tenure of the council.
Though she should have resigned on December 12 according to the seat sharing agreement within the LDF, a confusion over the position of standing committee chairperson between the CPI and the CPI(M) delayed the decision.
The first night shopping festival in the city, subway on MO Road, shifting of head post office for Pattalam road development, starting of the work of I.M. Vijayan sports complex at Lalur, are some of the achievements of the outgoing Mayor.