Deputy Chief Executive David Stout will leave his position at the NHS Confederation to head up two commissioning support units (CSUs).
Stout said it will be a "big wrench" to leave the organisation but is "excited" by the new challenges. "I have really enjoyed my time at the NHS Confederation," he said.
"It has been a great privilege to represent both primary care trusts and the wider NHS on the national stage.
"It will be a big wrench to give up the job but, after five years, it's time to take on new challenges.
"I am really excited to have been given the chance to lead the two CSUs in Essex and Hertfordshire. I am sure we can make a huge contribution in the new reformed NHS."
Stout was appointed deputy chief executive of the NHS Confederation in October last year. He held the position as director of the organisation's primary care trust network from 2007.
Chief Executive of the NHS Confederation Mike Farrar praised Stout for his contribution in explaining the organisations more "complex and controversial" NHS decisions to the public and said his departure leaves him with "a big job to fill".
Two of the 23 NHS CB hosted CSUs, the Essex organisation will serve a population of around 1.8 million and the Hertfordshire CSU a population of around 1.2 million.