Kirklees Council leader Mehboob Khan is stepping down for a new job in London.
The Labour councillor will leave his leader post at the end of February.
He has been council leader for five years and a councillor for 17 years,
Coun Khan said: “I feel the time is now right to move on as I have had a fantastic time as leader of a large council in a time of immense change for local government.
“It has been a privilege to be a councillor for Greenhead ward and leader of my home authority – but it would not be right to be leader for ever when it is a role which demands such a huge amount.
“My new post in London will be an exciting challenge, working with council leaders, the Mayor of London and Westminster.
“But I have no doubt that my successor, once that person is in place, will have a strong platform to build from and lead Kirklees through its most difficult financial challenges in its history.”
Coun Khan will become a political advisor at the Local Government Association, specifically working with the London boroughs, the Mayor of London’s office and Westminster.
He added: “I would like to thank the many colleagues and friends who have supported me as a councillor and council leader, and especially the council staff who work so hard to deliver services to local people.
“While this has been a very difficult decision for me personally, my new role is an exciting challenge at the right time.
“You can only do such a high pressure role as council leader for so long while being as effective as possible, and I am confident that whoever my successor is, they will be able to take the council through the new challenges it is facing.
“However, until I stand down, it is business as usual for all of us, with the most important decision on the next budget being taken next month.”
As well as Kirklees leader, Coun Khan is chairman of the West Yorkshire Fire Authority, vice-chairman at the Local Government Association and sat on the local health board.
The Labour Party will now have to select a new leader.
The Full Council will vote to decide if the Labour leader should become Council Leader.
Heckmondwike councillor David Sheard is the current deputy leader of Kirklees Council.