Mike Jefferies will join the union's Executive Board and will become Company Secretary to WRU Ltd and the Millennium Stadium plc. He is currently a partner with the law firm Hugh James in Cardiff and for more than a decade has played a major role in handling legal and business affairs issues for the WRU.
One of his most high profile projects was overseeing the legal detail of the deal to fund and complete the building of the Millennium Stadium. His appointment to the WRU follows the recent recruitment of Steve Phillips as Director of Financial Affairs, John Williams as Head of Communications and the appointment of Gerry Toms as General Manager, Millennium Stadium.
Group Chief Executive of the WRU Roger Lewis said: "We are delighted to have been able to recruit a solicitor of Mike's stature as our new Head of Legal Affairs.
"Apart from his undoubted talent and expertise as a lawyer he also upholds the values of integrity, honour and determination to succeed that we at the WRU hold dear.
"As a partner at Hugh James Mike's advice to the WRU on so many matters in recent years has been decisive and intelligent. During the course of my first five months at the WRU his support has been invaluable.
"Going forward he will now be able to play a key role in advising on major decisions at the primary stage of the corporate process. Business life moves quickly in the modern world and it is vital the WRU can act decisively and correctly at the speed required to achieve the best results for the union, the players and the fans."
Mike Jefferies said: "Through my professional association with the WRU over the years I am fully aware of the exciting opportunities and challenges the future will now hold for me.
"It has always been a vibrant and dynamic organisation which is now going through a new process of change to meet the constantly shifting demands of the professional game.
"As Head of Legal Affairs I will be able to get involved at all levels of the organisation to give advice and guidance wherever it is required. I am doubly delighted because throughout my life I have been a devoted follower of the game and have enjoyed 30 years as a supporter and member of Cardiff Athletic Club."
Mike Jefferies was born in Crickhowell and was educated at King Henry VIII school in Abergavenny before studying Law at University College London. He joined the Hugh James law firm in 1969 and became a partner in 1972 as soon as he qualified as a solicitor.
Throughout his career he has earned a reputation at the forefront of the legal profession in Wales featuring in both the Legal 500 and the Chambers Guide to the legal profession. As well as the WRU his clients over the years have included the University of Aberystwyth, Glamorgan County Cricket Club, Welsh Water Dwr Cymru, The Environment Agency and Cardiff Council.
Gareth Williams, the Senior Partner at Hugh James, said: "Mike is an outstanding lawyer who has earned immense respect throughout his career from people inside and outside the profession. He has helped Hugh James become one of the leading law firms in Wales with a reputation which stretches far beyond the principality.
"We are all delighted at his success and wish him well in his new path with the sure knowledge that his presence will only help and enhance the reputation of the WRU.
"We are particularly pleased that the dynamics of his new position will enable him to retain a professional association with Hugh James who are very proud of their role as advisers to the WRU."
Mike Jefferies will take up his appointment with the Welsh Rugby Union in May this year.