The trio of men, who are all in their 20s, were arrested in south-east London on Saturday three days after 25-year-old Lee Rigby was hacked to death in Woolwich.
"Three men who were arrested on suspicion of conspiracy to commit murder in connection with the killing of Drummer Lee Rigby have been released on bail," the Metropolitan Police said in a statement.
"They have been bailed to return to a south London police station," the statement said.
Meanwhile, two people have been arrested on suspicion of arson after a fire was discovered yesterday at the Grimsby Islamic Cultural Centre in Weelsby Road.