The tweet, posted at 9.46pm last night, as South Africa's president Jacob Zuma was announcing Mandela's death, was retweeted more than 77,000 times.
Previously the highest number of retweets for a single tweet on the @BBCBreaking account was just under 20,000 shares.
Mark Frankel, assistant editor of social news at the BBC, explained that the tweet had been set out in a way to maximise the number of shares.
“We tweeted a photo of Mandela and kept the tweet quite short to allow people to add in their own comments,” he said.
Frankel added that the BBC had also received a lot of shares and interactions with content posted on its Facebook and Google+ pages, as well as three short video clips on the BBC News Instagram page.
Nelson Mandela, South Africa's first black president, dies aged 95 pic.twitter.com/uUQOB2F4x7— BBC Breaking News (@BBCBreaking) December 5, 2013
“The Instagram page was started quite recently and has already been quite successful in terms of highlighting the best of BBC video," he said. "It's been very popular with a younger audience.”
While the BBC waited until Zuma's announcement to confirm Mandela's death, Channel 4 hinted at the news early on with a tweet at 9.36pm GMT saying that a “big announcement [was] imminent” outside the home of Nelson Mandela”.
“In terms of UK news, I'm sure we [made the announcement] pretty early if not first thanks to our sources in South Africa,” said head of online at Channel 4 News Anna Doble.
“We had a tip-off from our sources in South Africa that there would be an announcement from Jacob Zuma and tweeted that straight away, which got a lot of comments and interactions.”
“We then confirmed Mandela's death following Zuma's announcement, nine minutes after the initial tweet.”
@Channel4News account relating to Mandela's death received around 1,500 retweets.
Channel 4 also broadcast an hour-long lunchtime special dedicated to Nelson Mandela, with half an hour being shown on TV followed by half an hour online.
In addition to live-streaming coverage from outside Mandela’s home in South Africa, the broadcaster has also created a Nelson Mandela YouTube playlist and tomorrow will publish an interactive map featuring all the London street names that feature Mandela's name.
However, Doble noted that despite large amounts of social sharing, Channel 4's Nelson Mandela content had still not received as much traffic as stories on the east coast storms according to last night's statistics.
Frankel also highlighted the need to balance the Mandela story with other coverage of importance, such as the east coast storms and the Autumn statement.
“We don't want to short change our audience,” he added.
Corection: This article has been updated to show the previous record for shares of a tweet from the @BBCBreaking account is just under 20,000 shares, not just under 23,000, as previously stated.