The peak audience of 1.1 million during the Wales v England match is the third highest TV audience in Wales this century.
The Group Chief Executive of the Welsh Rugby Union, Roger Lewis, said: ''On Saturday Wales was one.
"A nation came together in a passionate display of unity. Together we celebrated possibly Wales' finest ever rugby occasion.
"The BBC captured it all brilliantly as only they can. The most amazing of scenes of jubilation and celebration were beamed around the world.
"At the centre of it all was one of the most extraordinary rugby matches played in our great stadium. If anyone ever doubted the absolutely unique place rugby occupies in the hearts and souls of the people of Wales, just go to the BBC iPlayer now. "
Geoff Williams, Head of Sport at BBC Cymru Wales said, "These extraordinary figures reflect the public's passion and pride for Welsh rugby and is an indication of the appreciation of the BBC's expert coverage. The occasion, especially the singing of the anthems, transcended mere sports coverage - it was a national event.
"In the wake of Saturday's result, it is perhaps all too easy to forget that our coverage of the campaign is such a central part of what makes the tournament so special for so many in Wales. It was the concluding chapter of two months of comprehensive coverage across all our services."
The number of people who watched in Wales means more than a third of the 2.9 million population were watching the rugby action.
Across the UK on the BBC a peak of close to 9.5 million people were watching the match which decided the outcome of the competition with Wales chasing the championship and England hoping to secure the Grand Slam.
Around Wales the colossal number of viewers was being seen as evidence that rugby union is thriving as the national sport of Wales.
The match was also viewed by a sell-out crowd inside the Millennium Stadium as all of the 74,500 seats were filled.
Events at the stadium also boost the Welsh economy with an independent survey commissioned by the WRU revealing that across an average year they contribute £100million to the south east Wales economy and sustain 2,400 permanent jobs.
The Millennium Stadium is also playing host to the opening ceremony of the Rugby League World Cup opening ceremony later this year with Wales playing Italy and England facing Australia at the Cardiff venue.
Earlier on March 30 all four regions in Wales will be playing at the stadium on the same day in the Rabodirect Pro12.
The day long festival of rugby is billed as Judgement Day with the Newport Gwent Dragons tackling the Scarlets (KO 2.30pm) before Cardiff Blues take on the Ospreys at 5.15pm.
The 10 highest BBC1 audiences in Wales since 2000
(all based on highest quarter-hour audience):
|1||2012 Olympics Opening Ceremony||1.43m|
|2||2012 Olympics Closing Ceremony||1.33m|
|3||RBS 6 Nations 2013: Wales v England||1.1m|
|4||Euro 2004: England v Portugal||1.09m|
|4=||Eastenders Christmas Day (2002)||1.09m|
|6||Eastenders Live (Feb 2010)||1.08m|
|7||Eastenders (Mar 2001)||1.07m|
|8||Only Fools and Horses (Xmas 2002)||1.05m|