Sadiq Khan visited Gatwick on 15th July to praise the airport’s decision to increase its investment scheme by an additional £200m over the next five years.
The mayor also used the visit to call on Mrs May to rule in favour of a second runway for Gatwick in order to support the capital’s economy.
“Gatwick is the front door to London for millions of visitors to our city and I salute their decision to spend another £200m on improvements to the airport.
“They have put together a formidable plan that is a fantastic display of their confidence in London.
“The new prime minister has a very important decision to make regarding new airport capacity, and I urge her to rule as swiftly as possible in favour of a second runway at Gatwick, which would bring substantial economic benefits."
The new investment will see a total of £1.2bn invested over the next five years.
The airport plans to invest a total of £2.5bn from the time of its move to new private ownership in 2009 through to 2021.
The new improvements will include expanding both north and south terminal departure lounges, upgrading shopping facilities and additional aircraft parking stands.
Stewart Wingate, CEO of Gatwick Airport, added: “As Gatwick rapidly approaches full capacity, this increased investment paves the way for our second runway project.
“As we enter a new era for Britain, we must be agile and decisive as a country to show the world that we are open for business.
“It is now clear that only Gatwick can deliver the runway Britain needs to boost international competitiveness and trading links at a time when it is most needed, and we can do that before 2025.”