Ed Richards will stand down as CEO at the end of December after eight years at the helm.
Ofcom has yet to recruit a successor to Richards, who will continue to lead on all operational, financial, economic, competition and policy matters until his departure at the end of the year.
Patricia Hodgson, Ofcom chairman, said: 'Ed has been an outstanding Chief Executive. Under his leadership, Ofcom has helped to deliver superfast broadband, 4G, lower prices, innovation, competition, and sustainable public service broadcasting in the UK.
'He leaves an impressive legacy. On behalf of the Board I would like to thank him for his enormous contribution.'
Ed Richards said: 'It has been a privilege to lead Ofcom during such an exciting and dynamic period in the evolution of the UK’s communications sector.
'It is never easy leaving a job that you enjoy greatly but I have always felt that once I had completed eight years as Chief Executive this would be the right time to move.'
Richards joined the board in March 2003. He was promoted from COO to CEO in October 2006.
Commenting on the news of Ed Richards departure Matthew Howett, practice leader, Ovum said: ‘Following his tenure, the UK now boasts some of the lowest prices for telecommunications services in Europe, together with 4G and fibre at speeds and availability levels far greater than anyone could have anticipated just a few years ago.
‘Nevertheless, Richards is likely to remain frustrated with the lack of progress in two particular areas. The first is the ongoing threat of litigation that has dogged the sector which has been costly both in terms of legal fees and also the time Ofcom has had to dedicate to defending its decisions. Whoever replaces Ed Richards has their work cut out over the next few years.’