The Queen's funeral was watched by an average of 26.2 million people across all channels, according to the Broadcasters' Audience Research Board (BARB).
The service was broadcast simultaneously on a range of networks, including BBC One, BBC Two and BBC News; ITV along with ITV2, ITV3 and ITV4; and Sky News and Sky Sports.
Culture Secretary Michelle Donelan gave the figure the morning after the nation's longest-reigning monarch was buried at Windsor Castle.
Ms Donelan said her department was still "crunching the numbers" but that she believed it was around 250,000.
About 100 presidents and heads of government joined the 2,000-strong congregation at Westminster Abbey, which included US President Joe Biden and his wife, Jill, French President Emmanuel Macron, New Zealand prime minister Jacinda Ardern and the Canadian prime minister Justin Trudeau.
Tens of thousands of mourners flocked to London and Windsor to witness the state funeral as well as to catch a glimpse of the coffin as it was driven to St George's Chapel for the committal service in the Berkshire town.
The Queen's Coronation in 1953 was the first to be televised, reaching over 27 million in the UK and millions more abroad.
The late monarch's funeral was the first state funeral held in Britain since Sir Winston Churchill's in 1965.