The City of London police said 20 people had been arrested as officers removed tents and equipment from outside the 300-year-old church, where demonstrators had camped since mid-October.
As riot police surrounded the encampment, bailiffs in fluorescent jackets hauled camping equipment into waiting trucks and refuse bins -- though there was little sign of the violence that has accompanied the clearance of several Occupy sites in the U.S.
Protesters waved flags and banged tambourines, though a small number crafted a makeshift wooden structure opposite the cathedral and scaled it in an attempt to obstruct the eviction.
Britain's High Court last Wednesday rejected the protesters' legal challenge to an eviction order. Local authorities claimed the camp had harmed nearby businesses, caused waste and hygiene problems, and attracted crime and disorder.
"It's really sad what's happening today but I think we can be proud of what we've achieved," said Kai Wargalla, a 27-year-old student from Germany who had camped outside St. Paul's since October. "Our community is being attacked here, but we're going to reconvene and come back stronger."
Wargalla said she expected some demonstrators to join a smaller protest camp at Finsbury Square, close to financial and legal companies in central London. Others insisted that protesters would return to continue to meet outside St. Paul's, though they would no longer attempt to camp there.
"It's only tents and materials the injunction applies to so I think some protesters will be back," said demonstrator Gary Sherborne, 50.
The City of London Corporation, the local authority that secured the eviction, said it hoped to reopen the area around St. Paul's to tourists and local workers as soon as possible. Parts of surrounding streets had been barricaded to contain the size of the encampment.
"It is regrettable that it had to come to the need for removal but the High Court judgment speaks for itself," said Stuart Fraser, of the City of London Corporation. "The site has now been cleared and the area is undergoing a deep clean."
Protesters set up camp outside the cathedral after they were thwarted in an attempt to demonstrate in front of the nearby London Stock Exchange.
Their proximity to Christopher Wren's architectural icon embroiled the church in a conflict between bank-bashing protesters and the city's finance industry. The church's position on the protesters has shifted several times, and the cathedral's dean and a senior priest both resigned over the impasse.
"Riot police clearing the steps of St. Paul's Cathedral was a terrible sight. This is a sad day for the Church," said Giles Fraser, who resigned as canon chancellor of St. Paul's in solidarity with the protesters.