"A team from Scotland Yard arrived in Rabat on Monday and Lee Murray's extradition is expected in the evening because he is the subject of an international warrant," a police official said on Monday.
Lee "Lightning" Murray, 26, from Sidcup in south London, was detained in the Moroccan capital on Sunday over the daring heist four months ago at a Securitas warehouse in Tonbridge, southeast of the British capital.
The robbers made off with a record 53 million pounds ($96.94 million).
He was arrested by Moroccan police at the Mega Mall shopping centre in the posh Souissi district of Rabat, along with three others who are not believed to be wanted by British police.
In a statement, the Moroccan police said they had been tracking the suspects for four months.
"Due to the danger posed by the suspects, specialists in martial arts and firearms, Moroccan police had to use special techniques to neutralise them ... without posing a risk to citizens nearby at the time of the arrest," it said.
Murray is a cage fighter - a sport in which contestants trained in a variety of martial arts face off inside a steel cage.
Britain has no formal extradition treaty with Morocco, so it would have to make a special, one-off request.