Deputy mayor for transport, Heidi Alexander, is to step down from her post at the end of the month.
Mr Khan thanked Ms Alexander “for her exceptional service to London” and said: “Heidi has worked tirelessly during the last three and a half years.
“In particular, I’d like to pay tribute to her for tirelessly leading TfL through the pandemic - the most difficult period in its history.
While Ms Alexander said: “It has been an enormous privilege to work with Sadiq and so many brilliant colleagues at both TfL and City Hall during the last three and a half years.
“I am tremendously proud of the way we kept London moving through one of the most difficult periods in its history.”
And Mr Dance said: “I look forward to continuing Heidi’s fantastic work. London is without doubt the greatest city in the world – and I am looking forward to working with TfL to deliver a world-leading transport system.”
It comes as the government has extended its funding support for Transport for London (TfL) services until February 4 2022, in the midst of contentious negotiations over a future funding deal for the service.
TfL had warned it would have to potentially close an entire Tube line if a funding deal couldn’t be reached, while the mayor has also proposed a £20 council tax rise over three years to help cover the £1.9 billion funding gap.
The mooted three year hike in council tax would raise an estimated £172 million annually comes as the mayor has refused to increase fare prices but has warned of cuts to bus and tube services, leading to “managed decline.”
Free travel for over-60s may also need to be phased out, and other proposed changes include applying all-day peak fares to Heathrow on the tube, raising the price of an Oyster card deposit, and stopping the use of rail travelcards to reduce ticketing costs.
Analysis from City Hall has projected that if the government failed to give TfL funding, it could cost the city more than £12 billion over the next 10 years.
Mr Khan said: “The Government is still refusing to properly fund TfL which has been severely affected by Covid-19, yet again only providing a short-term funding deal that will only last a matter of weeks.
“This means that nothing has changed in terms of TfL having to plan on the basis of a managed decline of the capital’s public transport network.
“As a condition of the emergency short-term funding TfL needs to avoid collapse, the government is forcing us to raise additional revenue in London through measures, like council tax, that will unfairly punish Londoners for the way the pandemic has hit our transport network.
“Despite these measures, only a long-term funding deal with the government, including additional capital funding, will be enough to avoid significant and damaging cuts to tube and bus services.”
Andy Byford, London’s transport commissioner, said: "There is no UK recovery from the pandemic without a London recovery and there is no London recovery without a properly funded transport network in the capital.
“It is therefore essential that discussions with the government continue so that we can agree the sustained long-term Government funding that is vital for the coming years if a period of ‘managed decline’ of London’s transport network is to be avoided.
“Working together we must achieve this longer term funding settlement that ensures London’s transport network can remain reliable and efficient, can support the jobs and new homes that rely upon it and can support the economic recovery of the capital and the country as a whole.
“This vital job is far from done."
A Department for Transport (DfT) spokesperson previously said: “We have repeatedly shown our commitment to supporting London’s transport network through the pandemic, providing more than £4bn in emergency funding to TfL.
“We will continue to discuss any further funding requirements with TfL and the mayor, and any support provided will focus on getting TfL back onto a sustainable financial footing in a way that is fair to taxpayers across the country.”