The United Kingdom will resume efforts to deport him to Jordan, the government said.
Britain views Abu Qatada as a national security threat, but the European Court of Human Rights barred the country from deporting him because evidence gained from torture could be used against him in Jordan, where he has been convicted in absentia of involvement in terrorist conspiracies.
But Jordan has outlined a number of conditions that Home Secretary Theresa May said means the deportation could now go ahead.
Qatada will be tried in public before civilian judges, and the existing conviction against him will be quashed, she told British lawmakers Tuesday.
"The assurances and information that the government has secured from Jordan mean that we can undertake deportation in full compliance with the law and with the ruling of the European Court of Human Rights," said May in a statement to the House of Commons.
"Deportation might still take time -- the proper processes must be followed and the rule of law must take precedence -- but today Qatada has been arrested and the deportation process is under way."
Jordanian Justice Minister Ibrahim Aljazy had said after Britain announced the arrest that Jordan would detain Abu Qatada and give him a full trial when he arrived in the country.
The two countries have been in talks since the Court of Human Rights ruling earlier this year. Both sides want him sent to Jordan.
But he can still appeal to stop his deportation, a process that could take months, May said.
Assem Rababah, a lawyer representing Abu Qatada in Jordan, told CNN it was too early to judge when his deportation might occur, as British legal proceedings were still ongoing.
He said that when the deportation order was final, a team of officials and doctors would travel from Jordan to Britain to assess Abu Qatada's mental and physical health.
Abu Qatada was released from a high security prison on bail in February.
He had been imprisoned in Britain for six years while the government worked to send him to Jordan, where he holds citizenship.
The British government claims Abu Qatada has raised money for terrorist groups, including organizations linked to former al Qaeda leader Osama bin Laden, and has publicly supported the violent activities of those groups.
Abu Qatada has denied the allegations against him.
Also known as Omar Othman, Abu Qatada arrived in the United Kingdom in 1993 and applied for asylum on the grounds that he had been tortured by Jordanian authorities. He came to Britain on a forged United Arab Emirates passport, according to court documents, and claimed asylum for himself, his wife and their three children.
The British government recognized him as a refugee and allowed him to stay in the country until 1998.
Abu Qatada applied to stay indefinitely, but while his application was pending, a Jordanian court convicted him in absentia on charges related to two 1998 terrorist attacks and a plot to plant bombs to coincide with the millennium.
He was released briefly in 2005 after the repeal of the anti-terrorism law on which he was being held. British authorities ordered his renewed detention that year under the Prevention of Terrorism Act, according to the European Court of Human Rights.
