Announcing her retirement , Dame Gillian Morgan said:
"Taking the decision to retire from the role of Permanent Secretary has not been easy. There is nothing more important to me than the long-term future of Wales and the people who live here.
"It has been a great honour for me to lead an organisation that is committed to supporting Ministers to improve the lives of the people of Wales.
"I am immensely proud of what we have achieved over the past five years, particularly against a very challenging financial and economic environment. By working smarter, we have delivered improved efficiency right across the organisation, whilst also achieving a significant reduction in our running costs.
"Over the past 22 years I have been involved in managing a number of major organisations at Board or Chief Executive level but I can honestly say that leading the Welsh Government Civil Service has been one of the most fulfilling and exciting parts of my career."
Commenting on the Permanent Secretary’s announcement, First Minister Carwyn Jones said:
"I want to thank Gill for the commitment she’s demonstrated in her time as Permanent Secretary.
"Dealing with the financial challenges of the past few years hasn’t been easy, either for Ministers or the Civil Service, and Gill has led the organisation through a period of significant downsizing while remaining focused on what we’re trying to achieve through the Programme for Government.
"I know my Cabinet colleagues and everyone who works here will join me in thanking her for everything she’s done.
"Good and effective leadership of the Civil Service is absolutely critical in supporting Ministers to do what they were elected to do and it’s essential that whoever takes over from Gill has the right skills and experience to take on one of the biggest jobs in Wales."