More than 13 million viewers tuned in to see the first airing of the Band Aid 20 video, Do They Know It's Christmas?, on the five main TV networks.
Will Young and Jamelia duetted for their line of the song
It was shown simultaneously on BBC One, BBC Two, ITV1, Channel 4 and Five. The figures do not include Sky One or the other digital channels which showed it.
Pop star Madonna, who does not appear on the track, urged fans to "feed the world" before Thursday's screening.
The single is due to be released on Monday 29 November.
BBC One was the most watched terrestrial channel while the video aired, with 3.9m viewers, according to unofficial overnight figures.
ITV1 drew in 3.1m viewers and BBC Two was seen by 2.6m. Just over 1m tuned into Five and Channel 4 incorporated the screening into the end of the Richard and Judy programme, which attracted 2.6m people.
The video began with Coldplay's Chris Martin in the main hall of Air Studios, north London, where the song was recorded at the weekend.
It also featured some stars whose voices did not appear on the song - including Sir Paul McCartney playing bass, Radiohead's Thom Yorke on piano and Blur's Damon Albarn, who served tea.
The video included footage of organiser Bob Geldof in the studio playing the stars a video of an emaciated young girl in the 1984 Ethiopian famine.
Madonna recorded an introduction but did not sing on the record
The girl, now a young woman, was then introduced to the singers, many of whom were moved to tears.
Madonna's introduction began: "Twenty years ago, I performed at Live Aid and the world watched. You saw me and my generation demanding a change.
"Once again, here we are 20 years later," she said, over images of starving African children. "More people die of hunger in Africa than war and Aids put together.
"In a world of plenty, it is hard to imagine that most African children will go to bed tonight hungry.
"Bob Geldof and his friends are here to remind you that we can never forget. Not ever. Feed the world. I am honoured to introduce Band Aid 20."
The song, a remake of the 1984 original, was recorded on Friday, Saturday and Sunday by more than 50 artists including Joss Stone, Dizzee Rascal and The Darkness.
It is tipped to be the Christmas number one, but bookmakers have shortened the odds on the track's long-term success after it received lukewarm reviews.
The single, which also features Bono, Sugababes and Will Young, was made available to download from the internet on Thursday from a number of music services that will donate proceeds to the cause.
It is also being launched as a charity mobile phone ringtone with proceeds going to the Band Aid Trust, which is supporting food aid to the Sudan's troubled Darfur region.