NHS Direct chief executive Matt Tee is leaving the service to take up the most senior communications role in the civil service.
Mr Tee, who joined last May, was today named as the next permanent secretary for government communications.
He said: "I have really enjoyed being chief executive of NHS Direct and it will be a great wrench to leave.
"This new role is the only one I would have considered applying for - it is the most senior role in public service communications and I felt I had to go for it."
Mr Tee will replace Howell James in the role, which has responsibility for the strategy, co-ordination and effectiveness of communication across government.
NHS Direct chair Joanne Shaw said: "Matt leaves NHS Direct well placed to take advantage of the opportunities offered by the Darzi report and the developing digital NHS."
It was this week confirmed that the organisation had dropped plans to become a foundation trust because of government reluctance to free it from central control.
Mr Tee, whose departure date has not yet been agreed, added: "I am really pleased with where NHS Direct has got to in my time and know that it will go from strength to strength from here.
"In the post-Darzi era, the role of telephone, internet and mobile communications in providing high-quality healthcare will undoubtedly grow enormously and NHS Direct is well placed to be at the forefront of that development."
Mr James was the first person to hold the permanent secretary role after it was created in 2004 on the recommendation of an independent review of government communications. He left in June.