S4C will show every Cymru match in the Guinness Six Nations for the next four years.
The Welsh language broadcaster will be the only place to watch live coverage of every Cymru match, after securing an agreement with the BBC and ITV, the primary rights holders.
S4C's Clwb Rygbi Rhyngwladol, will bring live coverage, analysis and reaction to every match, starting with Ireland v Cymru on Saturday 5 February.
Catrin Heledd, Clwb Rygbi Rhyngwladol host, said: "This is fantastic news for Welsh rugby. For a great many Wales supporters, it is the highlight of the rugby calendar.
"It is a privilege to be part of it and to be able to bring Welsh language coverage to viewers at home.
"Wales are the reigning champions and the competition is as fierce as ever. We hope you can join us in Dublin for the opener."
Clwb Rygbi Rhyngwladol, which is produced by BBC Wales, will also show two of Cymru's matches in the 2022 Women's Six Nations and three in the 2022 Under 20's Six Nations.
Sue Butler, S4C Sports Commissioner, said: "The Guinness Six Nations is an international rugby championship with unrivalled passion and excitement, and we are delighted to continue our long association with it.
"This new agreement completes a portfolio of rugby union on S4C which stretches from colleges, Premiership clubs, Regional in the URC and Europe, to International rugby.
"S4C is pleased to support our national teams and Welsh rugby across the board."
Steve Phillips, Welsh Rugby Union Chief Executive, said: "The provision of Welsh language broadcasting is a vital part of our strategy for the whole game in Wales and we warmly welcome this news from S4C.
"S4C play an integral part in supporting Welsh rugby from our club game, to our professional sides, our pathway teams and both our men's and women's international sides and we are very grateful for their continued backing in all of these areas."