The 95-year-old monarch has led the tributes to the 18-year-old tennis star, who ended Britain's 44-year wait for a women's Grand Slam singles champion with victory in New York City on Saturday night (09.11.21).
The Queen said: "I send my congratulations to you on your success.
"It is a remarkable achievement at such a young age, and is testament to your hard work and dedication."
The Queen also hopes that Emma's success at the US Open - where she defeated Canada's Leylah Fernandez 6-4 6-3 in the final - will inspire the "next generation".
She added: "I have no doubt your outstanding performance, and that of your opponent Leylah Fernandez, will inspire the next generation of tennis players."
Prince Charles and the Duchess of Cornwall have also offered their congratulations to the teenage star.
The royal duo wrote on their official Instagram account: "What a fantastic achievement! We are all so proud.
"Well done to @leylahannietennis today too. An outstanding match between two inspiring young women - we can't wait to see where you go next. (sic)"
Elsewhere, the Duchess of Cambridge - who is a patron of the All England Lawn Tennis and Croquet Club - congratulated both of the teenage finalists on their success at the US Open.
The Duchess wrote on Twitter: "Huge congratulations @EmmaRaducanu on your stunning performances and historic Grand Slam victory! Incredible –we are all so proud of you. @LeylahFernandez well done on your amazing achievements at this year’s #USOpen, it’s been a pleasure to watch. C (sic)"
Meanwhile, the Spice Girls hailed the US Open final as an example of "girl power".
The iconic pop group said: "Wow! Amazing tennis from @leylahfernandez and @EmmaRaducanu that’s Girl Power right there!! Congratulations Emma (sic)"