Scotland Yard has more than 5000 officers on duty for today's wedding and has pledged to take "robust" action against anyone threatening to disrupt the occasion.
Police sources said the raids were made as part of investigations into recent outbreaks of disorder in central London, including student and anarchist riots.
"These arrests are part of ongoing proactive work to tackle suspected criminality," a Scotland Yard spokesman said.
"They are not specifically related to the royal wedding but have been brought forward ahead of the event."
Police are imposing a tight security clampdown around the wedding of Prince William and Kate Middleton.
Snipers will take to rooftops and undercover officers will mingle among the crowds as part of a massive covert and overt operation.
Security against potential threats from Islamist extremists, dissident Irish republican terrorists, anarchists and even lone stalkers is being balanced with the desire to let onlookers enjoy the pageantry.
Officers have been scouring central London for explosives and hidden weapons in recent days, inspecting drains, lamp-posts and traffic lights.
Meanwhile, Kate Middleton waved to the crowds outside The Goring hotel in London as she made what was expected to be her final appearance before the wedding.
She was greeted by hotel owner Jeremy Goring as she stepped from a black Jaguar outside the entrance at 5.45pm (0345 AEST).
Dressed in a black and white spotted dress, she was accompanied by sister Pippa and mother Carole.
They were welcomed by a large crowd of enthusiasts who had waited outside the central London hotel all day for a glimpse of the bride-to-be.
The hotel had been the scene of frenetic activity all day as final preparations were made for Miss Middleton's arrival.
She is staying at the five-star Belgravia establishment, on Beeston Place, with her sister, brother James, her mother, and father Michael the night before she marries Prince William.
To ensure no-one catches a glimpse of her in her wedding dress before she arrives at Westminster Abbey tomorrow, a canopy has been erected over the front of the hotel.
It covers even the pavement outside to make sure she can enter the Rolls-Royce Phantom VI in which she will travel to the abbey with her father without any photographs being taken of her dress.
Beeston Place was closed to members of the public at 8am today. Large black bollards have been placed at either end of the road to prevent vehicles getting through without permission.
There has been a large police presence at the hotel during the day, with armed officers patrolling outside and sniffer dogs being led into the building.
Gardeners also worked on the front of the hotel, watering plants and tweaking the foliage outside.
Bay trees were seen being delivered to the hotel, as well as several large wooden and cardboard boxes.
The short street near Victoria station has become a focus for the world's media and royal fans alike.
