The 18-year-old, who won Saturday’s US Open final in straight sets, was hailed as “our new Queen of tennis” by supporters.
Throughout the match, support for Raducanu flooded in as UK fans united behind her.
Following her win, Boris Johnson praised her “extraordinary poise and guts”.
“What a sensational match! Huge congratulations to @EmmaRaducanu. You showed extraordinary skill, poise and guts and we are all hugely proud of you.”
A tweet from the official account of the Duke and Duchess of Cambridge congratulated the teenager and her opponent on their “amazing achievements” at the tournament.
“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”
TV presenter Gary Lineker also noted Raducanu’s “performance” and “triumph”.
“First time in my life I’ve ever tweeted whilst on air but my goodness what a performance, what a triumph, what an amazing young woman,” he said.
“Congratulations @EmmaRaducanu on a truly staggering achievement. US Open winner at 18 without losing a set.
Comedian Dara O Briain said: “Well that is both brilliant and ludicrously unbelievable. Well done Emma Raducanu.”
8 Out Of 10 Cats host Jimmy Carr described the teenager as a “legend” and admitted he had become emotional through the match.
“Emma Raducanu – 20 straight sets. What a performance? What a legend? The game I love played beautifully,” he tweeted.
“I think it’s ok I shed a tear. Congratulations Emma & also well done on those A Levels.”
Fellow Cats panellist Jon Richardson added: “What a treat and a privilege that was to watch.
“Thank goodness for sport in a messed up world and thank goodness for Emma Raducanu. Absolutely superb.”
Former Countdown host Carol Vorderman said: “Amazing…..huge congratulations to our new Queen of Tennis…. ”
But people also praised the standard of play on both sides of the net.
“Just incredible! @EmmaRaducanu is a star, a role model and a champion. Congratulations!” she tweeted.
“I suspect tonight is one of these sporting occasions that will be talked about for decades to come.
“Two great players who will no doubt dominate women’s tennis for years to come.”
TV presenter Nick Knowles tweeted: “The quality of the us open tennis women’s final is epic!”
Piers Morgan wrote: “BREAKING: @EmmaRaducanu wins the US Open.
“This is one of the greatest achievements in British sporting history. Congrats, Emma – you champion.”
Earlier in the match, leader of the Liberal Democrats Sir Ed Davey said: “What an absolutely amazing match – and what an amazing British athlete we have in Emma Raducanu.”