The mask-wearing rule on London Underground is expected to be dropped in line with the government's lifting of all coronavirus rules later this week.
Mayor Sadiq Khan said infection levels were falling in London and it was expected that wearing a face covering would no longer be a condition of carriage on the TfL network.
But despite the official guidance, Mr Khan urged Londoners to be considerate to other passengers and remember the health benefits of wearing a mask.
"We know that face coverings remain a simple, effective measure that give Londoners confidence to travel, and following clear advice from public health advisers, TfL will likely continue to recommend their use on the network.
"I urge passengers to be considerate of their fellow Londoners and continue to wear a face covering where appropriate unless exempt."
Mr Khan also said in order for restrictions to be lifted "in the safest possible way", the Government "must rethink its plans to abandon free testing" as well as ensuring financial support for those that cannot work from home if they test positive.
"We cannot have a situation where only the well-off can afford to ‘live with Covid’ safely or one where we’re not keeping an eye on new variants posing a risk to the country," he said.