Saturday's Six Nations decider saw a record-breaking peak audience of 9.63 million watch England v France, as the championship went down to the wire.
A peak of 4.1m watched Italy v Wales, while 5.1m tuned in for Scotland v Ireland and the BBC Sport website recorded its highest ever traffic on the day, with 8.22m unique UK browsers.
Barbara Slater, Director BBC Sport, said: "It's what the BBC is all about, bringing these great moments that unite the nation, making them available to everyone wherever they are."
She added: "What an amazing end to such a thrilling Six Nations championship, and duly reflected in such a huge audience figure of 9.63 million on BBC One, with millions more accessing content through radio, online and digital platforms."
The online record beats the previous record of 8.03 million during the London Olympics in 2012.
In addition there were 4.4 million mobile browsers on Saturday - the biggest-ever UK mobile day on record for BBC Sport, beating four million for the first time. The previous record was 3.9 million on 1 February this year.
The previous television viewer record for England v France saw 9.56 million tune in to watch in 2011.