The 23-year-old law student from Paris has been given permission to remain in the country just 24 hours but he has already threatened to defy the authorities and out-stay his welcome.
Mr Cohn-Bendit - who is a German citizen - was expelled from France on 21 May for being the ringleader of the French student demonstrations, which almost brought the country to a standstill last month.
Angry about the Vietnam war and political stagnation, he led the occupation of the university at Nanterre and students at the Sorbonne quickly followed.
The violence which police used to suppress the protesters brought French workers onto the streets in their support.
A "back me or sack me" speech from President Charles de Gaulle led only to more violence and eventually order was restored on 29 May when tanks were ordered onto the streets of the outskirts of Paris.
Fears of unrest
Mr Cohn-Bendit, also known as Danny the Red because of his red hair, has today staged a sit-in at the BBC's Television Centre building in Wood Lane, West London.
In an interview with the BBC, he denied coming to Britain to cause trouble and shrugged off news of death threats made against him.
He said: " Two years ago I came here and nobody said a word, it is strange, they are telling me I am only allowed to stay 24 hours.
"We don't care about frontiers and I don't know how long I will stay, it depends what I have to do. I don't see why I shouldn't stay longer. I think it's a free country."
Rioting has been continuing in France, though on a lesser scale than before. There has also been speculation the rebel student was planning to stir up trouble here.
Mr Cohn-Bendit said: "It is very interesting what people think I am doing. I should be really better than batman or superman. It's really amusing. They think I am organising world revolution."
He blamed the French police for provoking the protesters.
Daniel Cohn-Bendit
Daniel Cohn-Bendit: "They think I am organising world revolution"
In Context
Daniel Cohn-Bendit's stay in Britain was extended to 14 days during which time he and a group of supporters visited Karl Marx's grave where they sang the protest song Internationale.
He eventually returned to Paris but was deported to West Germany in April 1969. Although he had been born in France, he became a German citizen. His parents were German Jews who had fled during the war but went back to live there in 1958.
He settled in Frankfurt where he became a teacher, ecologist and municipal councillor.
He was elected as a German MEP for the Green party in 1994 - then switched to stand in France, by invitation, as a Green MEP in 1999. In 2001 he was elected co-leader of the Greens in the European Parliament.
He has spoken of applying for French citizenship in order to run as mayor of Paris.
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Students man the barricades in Paris
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