The BBC said a mystery donor gave £5.5 million to the BBC's Sports Relief appeal, pushing the total from last night's telethon to £19 million.
Organisers are investigating whether the money, described as from a "good friend of Sport Relief" is the largest single donation to any telethon held in the UK.
Former England footballer Alan Shearer kicked off the night with a marathon cycle ride with TV presenter Adrian Chiles, which finished in the capital after they cycled 335 miles from Newcastle to London.
The television appeal, presented by Richard Hammond, Gary Lineker and Davina Mccall, also featured Sports Relief-themed editions of Strictly Come Dancing, The Apprentice, Top Gear and A Question of Sport.
Former England cricketer Mark Ramprakash teamed up with Eastenders actress Kara Tointon to win Celebrity Come Dancing, while comic Jimmy Carr hosted a one-off episode of A Question of Sport which saw Gary Lineker, Sue Barker and boxer Ricky Hatton answer the questions.
And Jonathon Ross interviewed chat-show king Michael Parkinson, during which the two reminisced about boxing champion Muhammad Ali.
On Sunday, thousands of people are due to run a mile to raise more funds.