The mayor said the screening – expected to be the largest in the country – had been organised due to the Lionesses’ “incredible performances” and the nationwide interest in their progress.
On Wednesday night they moved a step closer to claiming the trophy by defeating Spain 2-1 at Brighton’s Amex stadium.
Mr Khan, speaking at Mayor’s Question Time on Thursday, praised the Lionesses’ "skill, stamina and spirit" and added: "Being 1-0 down with a few minutes to go, I was a bit worried. What a screamer from [Georgia] Stanway to win the game."
England will face either Sweden or Belgium, with the match kicking off at Bramall Lane in Sheffield at 8pm. The final will be played at Wembley stadium, on July 31.
In Pictures | Women’s Euro 2022 (Quarter-Final): England vs Spain
Entrance to Trafalgar Square will be on a “first-come-first-served” basis. In order to gauge demand, fans are asked to register their interest by 5pm on Monday. Registration does not guarantee entry but will ensure people receive updates about the event and help the Mayor’s office to plan for the screening.
Mr Khan said: “As a huge football fan, I have been swept away by the incredible performances of Ellen White, Lauren Hemp, Beth Mead and our wonderful squad.
“With Euros fever gripping the country, I am delighted that thousands of Londoners and visitors will be able to come together and cheer the team on to glory on Tuesday night.”
From Saturday, Trafalgar Square will be transformed into an official Uefa “Fan Party”. This free event, which will be open daily until July 31, will include a pop-up football pitch featuring exhibition games and football-themed activities.
The square will also host a free screening of the final, which kicks off at 5pm on July 31.