The museum was keen to keep the Tudor Heart as it believed there to be few surviving artefacts related to Henry VIII’s marriage to Katherine of Aragon.
Since the appeal, it said, more than 45,000 members of the public had contributed to the cause, helping it raise just over 10% of its £3.5m goal.
It also received £1.75m from The National Heritage Memorial Fund, which aims to save the UK’s most outstanding, at-risk heritage treasures.
Other donors include the charity Art Fund, the Julia Rausing Trust and The American Friends of the British Museum.
“I want to say a heartfelt thank you to everyone who supported our campaign,” Cullinan said.
“This beautiful survivor tells us about a piece of English history few of us knew, but in which we can all now share.”
Simon Thurley, chairman of the National Heritage Memorial Fund, said: “The Tudor Heart is an extraordinary insight into the culture of Henry VIII’s court, and I am delighted that Memorial Fund support will enable it to go on public display.”
The museum hopes to formally include the pendant in the collection later this year, and has plans for it to tour the UK in the future.