The BBC broadcast live from outside 10 Downing Street
Almost 10m people watched the BBC News special covering Gordon Brown's resignation and handover of power to David Cameron's coalition government.
An average of 8.9m tuned in to watch the full programme on BBC One which was broadcast between 1915-2100 BST on Tuesday, early figures show.
A peak audience of 9.9m tuned in at 2030 BST, while a further 1.58m watched the coverage on the News Channel.
EastEnders and Holby City were both moved from the BBC One schedule.
And the One Show was taken off air to allow the BBC News special to be shown on BBC One.
But the coverage prompted complaints from viewers who were angry at the changes to the BBC schedule.
WEDNESDAY RESCHEDULED TV
20.00 Holby City (Waterloo Road will be shown in two weeks' time)
21.00 Junior Apprentice (as billed)
22.00 BBC News (Extended by 15 minutes)
22.45 National Lottery (10 minutes later than billed)
There were 738 complaints from viewers unhappy that EastEnders was dropped, while 83 people complained that Holby City was not broadcast as billed. Both will be shown on Wednesday evening instead.
A further 400 people were unhappy at the schedule changes in general.
"This was a BBC News special on an historic evening, which covered Gordon Brown's resignation and David Cameron taking over as Prime Minister at the head of Britain's first coalition government since the Second World War," a BBC spokesman said.
"Audiences rightly expect BBC News to cover and explain such significant and complex events."
The figures for the news special were higher than the numbers who tuned in to watch the BBC's prime ministerial debate last month.
An average audience of 8.4m people watched the debate, which was broadcast on BBC One on 29 April - with the audience peaking at 9.1m viewers.
An average of 9.4m viewers tuned into the first ITV1 debate a fortnight earlier, while 4m watched Sky's offering a week later.