Ecuadorian President Lenin Moreno said that Assange's asylum was withdrawn following repeated violations of worldwide conventions.
Assange, 47, who has spent nearly seven years at the embassy after seeking refuge there to avoid extradition to Sweden, was detained after the Ecuadorian government withdrew his asylum, Scotland Yard said.
Wikileaks, however, is protesting Assange's innocence, and has claimed that Ecuador had acted illegally in terminating Mr Assange's political asylum 'in violation of worldwide law'.
Assange sought asylum at the embassy after he released thousands of secret documents through Wikileaks, some of which humiliated the U.S. government.
USA prosecutors have charged Assange with conspiring with former Army intelligence analyst Chelsea Manning to access a government computer.
"Assange's arrest will put him at risk of extradition to the U.S., where he will very likely face charges that could see him jailed for 30 or more years".
Assange took refuge in the embassy to avoid being extradited to Sweden where authorities wanted to question him as part of a sexual assault investigation.
He was apprehended outside the Embassy of Ecuador, where he had been evading an extradition request from Sweden since June 2012.
Unai Emery not anxious about Arsenal's away form
Aubameyang, Lacazette, Ramsey and Ozil must start together on Thursday, and if they do, Arsenal will win. Our home form is excellent, so I am pretty confident when we play at home.
In this file photo taken on May 19, 2017 Wikileaks founder Julian Assange speaks from a balcony at the Embassy of Ecuador in London.
According to The Guardian, in 2011, US autorities had opened a grand jury hearing to determine whether to prosecute Assange, as well as WikiLeaks for the release of government information. "Julian Assange, the hostile and threatening declarations of its allied organization, against Ecuador, and especially the transgression of global treaties, have led the situation to a point where the asylum of Mr. Assange is unsustainable and no longer viable", Moreno said in a video released on Twitter.
Moreno had cut off Assange's internet connection in the embassy in March 2018, making communication with the outside world hard.
"The discourteous and aggressive behavior of Mr Julian Assange" as well as "hostile and threatening declarations" by an unnamed organization against Ecuador made the asylum of Assange "unsustainable and no longer valid", Moreno said in a video message distributed via Twitter.
"Ecuador has made a sovereign decision to withdraw diplomatic asylum from Julian Assange over regular violations of global conventions", Moreno wrote on Twitter.
After Assange's arrest, the US Justice Department unsealed its indictment against him.
Hunt thanked Moreno for allowing police to arrest Assange at the embassy. "No one is above the law", he added.
The first warning that Assange would be evicted from the embassy came in the form of a thread of tweets from the official WikiLeaks account a week prior.