They have become the latest celebrities to apologise for "impersonating people of colour" on their TV show as Black Lives Matter protests continue across the globe.
The double act said they are "sincerely sorry to everyone that was offended" by the impressions on the "undercover" segment in old episodes of their ITV show Saturday Night Takeaway.
The pair darkened their skin and wore prosthetics for the sketches, in which they pranked famous faces while in disguise.
In a statement on Twitter, the pair wrote: "During past episodes of Saturday Night Takeaway we impersonated people of colour in the undercover segment of the show.
"We realise that this was wrong and want to say that we are sincerely sorry to everyone that we offended.
"We purposely stopped doing this several years ago and certainly would not make these sketches today."
The episodes have disappeared from ITV's online catch-up service, with the pair, both 44, confirming that they had "already taken steps to ensure the footage was taken down".
Ant and Dec wore blackface in 2003 as they dressed up as two fictional Jamaican women, Patty and Bernice, to prank Emmerdale cast members.
And in 2004, they dressed up as two Japanese girls, Suki and Keiko, using make-up and exaggerated accents.
Other celebrities, including Leigh Francis and Jimmy Fallon, have apologised for their portrayal of black characters as the Black Lives Matter movement gains momentum.
Francis, 47, posted a tearful video on his Instagram page saying sorry for "offensive" impressions of black people, including Craig David and Michael Jackson, on his Channel 4 show Bo' Selecta, which first aired in 2002.
He said he had "thought about things", adding: "I guess we're all on a learning journey."
In the US, reality TV show Cops has been dropped by its network Paramount and 1939 film Gone With The Wind has been temporarily removed by HBO's new streaming service because it includes "racist depictions".
In the UK, Little Britain and Matt Lucas and David Walliams's other sketch show, Come Fly With Me, were both removed from streaming platforms because of their use of blackface.
The programme has faced criticism in recent years for its portrayal of black and Asian characters by the two white men, with characters including a Caribbean woman called Desiree and a mail-order bride named Ting Tong.
Speaking to the Big Issue in 2017, Matt Lucas said that if he could make Little Britain again, he would not play black characters.
In an interview with Radio Times Magazine in 2018, Walliams said he would also make the show differently if he was given the opportunity.