Organiser of the wedding, which took place in Yesodey Hatorah Senior Girls' School in Stamford Hill, covered windows to stop people from seeing inside and could be fined up to $13,700.
British police have broken up a wedding with almost 400 guests in violation of Covid lockdown rules, which only allow six people to attend.
"This was a completely unacceptable breach of the law," said Detective Chief Superintendent Marcus Barnett on Friday.
"People across the country are making sacrifices by cancelling or postponing weddings and other celebrations and there is no excuse for this type of behaviour."
Weddings are currently supposed to take place only under "exceptional circumstances".
However, officers found hundreds of people gathering in Stamford Hill, in north London, with the windows covered to stop people from seeing inside.
Wedding at school
The organiser of the wedding now could be fined up to $13,700, and five others were issued $273 penalties.
The wedding took place at the Yesodey Hatorah Girls School, which serves Haredi Jewish families in the area, home to the biggest Orthodox Jewish community in Europe.
"We are absolutely horrified about last night’s event and condemn it in the strongest possible terms," the school said in a statement.
An outside organisation was responsible for letting out its hall and it had no knowledge of the wedding, the school said.
Coronavirus cases soared in Britain at the end of last year after the outbreak of a new, more contagious variant of the virus, which has led to the imposition of lockdowns across the United Kingdom.
The number of daily cases has fallen from a high of almost 70,000 on January 8 to just under 40,000 in recent days, but authorities are concerned that too many people are breaking the rules, meaning the virus keeps spreading.
On Thursday, British interior minister Priti Patel warned those who broke lockdown restrictions faced punishment by police and announced a new $1092 (800-pound) fine for those who attended house parties.