The Live 8 concerts attracted a peak audience of 9.6 million viewers on BBC One on Saturday evening.
Bono and Paul McCartney opened London's Live 8 concert
The channel's live coverage of the global concerts won an average audience of 6.6 million.
Rock band Pink Floyd's album sales soared by 1,343% after their comeback appearance at London's Live 8 concert.
Performers The Who and Annie Lennox also registered big sales increases. Meanwhile the BBC received 400 complaints after onstage swearing.
Saturday's average Live 8 ratings of 6.6 million represented 37.2% of the total TV viewing public at that time.
The Live 8 ratings failed to match the 20.7 million UK viewers who watched England's football defeat to Portugal in Euro 2004 last June.
They were also beaten by last year's finale of ITV1's I'm a Celebrity... Get Me Out of Here, which drew an average of 10.9 million viewers.
The 10 Live 8 concerts, aimed at putting pressure on the G8 leaders who are meeting in Gleneagles in Scotland, were broadcast by TV stations across the world.
More than 140 TV channels showed the events, along with some 400 radio stations, and internet streams.
Organisers estimated that 85% of the world's population would have been able to tune into the event.
Madonna and US star Snoop Dogg were among those to use bad language prior to the 2100 BST watershed.
The BBC, which did not use a time delay during the broadcast, apologised for the swearing.
A spokeswoman for the BBC said it had received "just under" 400 complaints about its Live 8 coverage.
LIVE 8 STARS' ALBUMS BOOST
1 Pink Floyd - Echoes: The Best of Pink Floyd - 1343%
2 The Who - Then and Now - 863%
3 Annie Lennox - Eurythmics Greatest Hits - 500%
4 Dido - Life For Rent - 412%
5 Razorlight - Up All Night - 335%
6 Robbie Williams - Greatest Hits - 320%
7 Joss Stone - Mind, Body and Soul - 309%
8 Sting - The Very Best of Sting & The Police - 300%
9 Travis - Singles - 268%
10 Madonna - Immaculate Collection - 200%
She added: "Millions of people enjoyed our 12 hours of live broadcasting.
"We are sorry if any offence was caused."
However the number of Live 8 complaints did not exceed the 4,000 complaints made to the BBC in May concerning its new 3D TV weather map.
The corporation also received 47,000 complaints before broadcasting Jerry Springer the Opera on 8 January, when hundreds of protesters rallied outside BBC buildings.
Current acts such as Razorlight and singer Joss Stone also enjoyed increased music sales following their Live 8 appearances.
Increased record sales for Live 8 performers, compared with sales last Sunday, were good news for "iconic acts" including Pink Floyd, according to HMV's Gennaro Castaldo.
"Even allowing for the relative nature of this exercise, where back catalogue sales of the more established acts are being measured from a fairly low base, this snapshot shows that Live 8 is having a marked effect on sales - just like its predecessor 20 years ago," he said.
Mr Castaldo added that the effect would become more pronounced during this week.