Transport Enforcement teams were located in the hubs of Stratford, Canning Town and Victoria.
They also patrolled buses, trams and DLR trains across the capital.
In Victoria, a team of four stopped anyone walking through the station without a mask and warned them that on the first day a reminder would be given, but after that fines would follow.
Officers shouted “face coverings are mandatory on the network” as commuters passed.
One of the law enforcement team members said, “Most people listen and are very good and apologize. We have had belligerents in the past, but today we ask people politely and they respond well. Maybe they missed the news or something, so we’re giving them a chance.
The team arrested dozens of maskless commuters despite the majority of people wearing masks.
Some even wore a gas mask-like device as the new Omicron strain of Covid hitting Britain increases concern.
The public address system and warnings on billboards emphasized that not wearing the required masks would not be tolerated.
Wearing a face mask has been a condition of travel on TfL services since Covid’s legal restrictions were relaxed in mid-July, but they were not required by law as they had been earlier during the pandemic.
Some people are exempt from wearing masks.
Most commuters praised the enforcement of the rules.
Margaret Traynor, 60, said: “People have to play by the rules. I’m glad TfL is stopping people.
George Savides, 22, said: “This is an important message, I am young but of course you have to wear a mask to protect others. “
A man who was arrested told the police, “I’m sorry, I just didn’t think I would forget in the future.
Some claimed to have had health problems but generally welcomed the intervention of the agents.
In Waterloo, notice boards were put up around the station and ticket agents were seen reminding people of the mask rules.
On the Jubilee metro line, a rough estimate based on passenger observation showed that eight in ten commuters were wearing masks.
The Mayor of London, Mr Khan, said: ‘Evidence shows that wearing a mask is the most effective public health measure in the fight against Covid. I welcome the government’s announcement that face coverings are now mandatory in shops and on public transport nationwide, as they are already on the TfL network. This is a measure that I have been calling for for a long time.
“With the proper enforcement powers, TfL will now be able to work with law enforcement partners and truly improve network compliance, the selfish few who refuse to wear a face cover face a fine,” rather than simply being denied access to transportation services. . TfL law enforcement officers will continue to monitor compliance across the network to ensure the safety of passengers and staff. “
Siwan Hayward, Director of Compliance, Policing, Operations and Security at TfL, said: “Throughout the pandemic, the vast majority of people have done the right thing and protected themselves from the virus. , for which we are very grateful. The government has now issued a regulation that means all customers must wear face coverings on public transport, unless they are exempted as part of the ongoing fight against Covid.
“Our enforcement officers and law enforcement partners will enforce this requirement, including denying access to our services and, with additional powers due to government regulation, imposing a financial penalty on those who refuse to comply. We will continue to monitor compliance across the network and take action to ensure the safety of our customers and staff on our network. “