Leader of North Lincolnshire Council, Councillor Liz Redfern, will step down from her role early in the New Year.
Councillor Redfern will announce her decision at the full council meeting on Thursday, December 15, with a new leader chosen at the same time.
The new council leader will take up the post on January 16, 2017.
Councillor Redfern will continue as a ward councillor for Axholme Central.
She said: “It has been a great honour and privilege to have led North Lincolnshire Council supported by colleagues and members of staff.
“I would like to take this opportunity to thank everyone for their contribution and commitment to making North Lincolnshire a great place to live and work.”