Anjem Choudary has been charged with three terror offences, police have said.
The 56-year-old was charged on Sunday with directing a terrorist organisation, being a member of a prescribed organisation and addressing meetings to encourage support for a proscribed organisation.
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Khaled Hussein, 28, who lives in Canada, has been charged with membership of a proscribed organisation.
The pair were arrested at Heathrow on July 17 after Hussein arrived on a flight.
They were held under section 41 of the Terrorism Act 2000 and remanded in custody.
They will appear at Westminster Magistrates’ Court later on Monday.
In a statement, the force said: “Counter-terrorism detectives have arrested two men as part of an investigation into suspected terrorism offences.
“The officers arrested a 56-year-old man from east London in the area at approximately 5:40 a.m.
“They arrested a 28-year-old Canadian national at Heathrow airport at approximately 12:35 p.m. after he arrived on a flight from Canada.
“Both were arrested on suspicion of membership of a proscribed organization, contrary to section 11 of the Terrorism Act 2000.
“The men are currently being held under section 41 of the Terrorism Act 2000 at a west London police station. Police searches of three addresses in east London are ongoing.”
Choudary, who was featured in Arab News’ “Preachers of Hate” series, is one of the UK’s most prominent Islamic extremists, heading up hate groups including Al-Muhajiroun.
The group, which was banned by the British government under anti-terrorism laws following the Sept. 11, 2001 attacks in New York City and the July 7, 2005 suicide bombings in London, has previously described the 9/11 attackers as “magnificent martyrs.”
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Choudhary was sentenced in the UK in September 2016 to five-and-a-half years for encouraging Muslims to join Daesh but served just under half of the sentence.