Ofcom chief Stephen Carter is to stand down after three years in the role.
Mr Carter will retain full powers until August 2006
Mr Carter, 42, was the regulator's first chief executive, taking up the post ahead of its creation in 2003.
It replaced five media watchdogs including Oftel and the Independent Television Commission when the organisations merged.
"Stephen took on an immensely challenging task - and has performed outstandingly," said Ofcom chairman Lord David Currie.
"His legacy is an effective and credible organisation which plays an important role in delivering greater choice, lower prices and greater innovation."
Mr Carter will step down in October, with the search for a successor due to begin in June.
The final decision will be approved by Culture Secretary Tessa Jowell.
Mr Carter, the former chairman of cable company NTL, will retain his full powers until August, when he will hand over to Lord Currie until the new chief executive is in place.
Ofcom is the independent regulator and competition authority for Britain's communications industries, with powers across radio, television, telecoms and wireless operations.