"John will join the company early in the New Year and will take up a seat on the new management board. This is a key strategic appointment and I am delighted to have attracted someone of John's experience and stature within the communications industry to take the post," said Mr Lewis.
"As well as a working lifetime of experience in journalism, John broadened his range of skills at ITV Wales to include mainstream management, budget control and strategic development.
"He has been Head of News for the past nine years managing a team of 45 journalists and technicians within a multi million pound annual budget.
"In 2003, ITV Wales News won the coveted Royal Television Society Regional News Programme of the Year Award for the first time and, over the past year, John has spearheaded a major restructure of the news operation including a £2.6 million investment in digital technology.
"Improving communications across the WRU Group, both within our national sport and at the Millennium Stadium, was one of the key tasks I was charged with when I took up my position. I am delighted John is joining us to oversee all internal and external media relations."
John Williams has more than 25 years experience of working in television news and as a journalist for Fleet Street and regional newspapers and magazines.
He started his journalistic career as a reporter on the South Wales Echo in Cardiff before gaining freelance agency experience in the Welsh capital.
In the early to mid 1980s he was based in London as a staff reporter for the Sunday Mirror. There he gained experience working in the UK and oversees on major news and feature assignments.
He headed up reporting teams on major news stories such as the Brighton Bomb outrage, worked on investigations and frequently operated as newsdesk cover in senior editorial roles. In the late 1980s he returned to Cardiff to run a freelance news and feature agency before entering television full time with HTV Wales.
Born in Merthyr Tydfil, John is married with two adult daughters. His wife, Julie, is Professor of Neuropsychological Genetics at Cardiff University School of Medicine.
"I am delighted to be joining the WRU Group in a role within which I feel I can make a major contribution to rugby in Wales and to the future development of the Millennium Stadium" said John Williams. "Rugby in Wales is well placed to make a giant leap forward as the game develops to embrace the professional era. I truly believe my deep knowledge of the media and my love of the game will help me meet the challenge of my new role with energy and focus.
"Rugby is more than just a sport in Wales and it will be an honour and a huge pleasure to be working at the heart of the organisation which runs the game and our great stadium.
"Wales has built an international squad which boasts fantastic strength in depth and a regional structure which is growing in power and support. It's a great story to share with the world.
"Alongside that we have a grass roots game and structure which boasts a proud history and provides a rock solid foundation stone for the sport. There are also some wonderful messages and stories to communicate regarding the Millennium Stadium and I will be seeking to build on the iconic image it has already created within Wales and beyond.
"I am fully aware of Roger's credentials and his ability and that was the catalyst which made me determined to get this job at the heart of the game I love."
The new Head of Communications will report directly to Roger Lewis on group strategy and will become a key player in the top level management team at the WRU. His appointment will be followed shortly in the New Year by that of a new Finance Director for the Group.
"The communications role is crucial to our continued success and I am delighted John has joined us," said Roger Lewis. "His experience of the media in Wales, and at a UK national level over a number of years, will serve to build us a communications structure fit to exploit all the opportunities which are ahead of us.
"This is a very exciting time for Welsh rugby and the Millennium Stadium and we are building fit-for-purpose teams both on and off the field to meet all our challenges head on.
"I am so grateful for the support and help I have had from everyone I have met so far in my tenure as Group Chief Executive. Many of the things I have been told have helped shape my vision for the future and I am determined to deliver for the sake of every fan and every player."
Commenting on the appointment of John Williams the Controller of BBC Cymru Wales, Menna Richards, said: "I would like to offer my warmest congratulations to John as the WRU Group's new Head of Communications. John was Head of News at HTV Wales (now ITV Wales) when I was Managing Director.
"He is a highly-regarded, experienced professional who inspires loyalty in his staff. I wish him well."
Elis Owen, the Managing Director of ITV Wales added: "John is an excellent appointment for the Welsh Rugby Union and Millennium Stadium. I have worked with him for a number of years and he's a well respected journalist and communicator and has a great knowledge of all aspects of the media.
"Over the last year he has been an inspirational leader of our new digital newsroom project and has served ITV Wales well as the Head of News. ITV Wales looks forward to co-operating with him in his new job."