The teenager from Kent, who had to qualify for the event and was only competing in her second major tournament, defeated the Canadian 19-year-old 6-4 6-3 to write herself into tennis' history books.
Raducanu, ranked 150 in the world going into this competition, is the first British woman to win a Grand Slam singles title in 44 years, the last person to do so being Virginia Wade at Wimbledon in 1977. She is the first qualifier – male or female – to win a Grand Slam in the open era.
In an extraordinary three weeks in New York, Raducanu did not drop a single set in ten matches across qualifying and the main draw. She overcame six top-50 opponents from the first round proper onwards, with Fernandez, ranked 73, the lowest-rated opponent she had to face in the main draw.
The match was preceded by a service to commemorate the 20th anniversary of the 9/11 terror attacks in New York, before the players took their place on Arthur Ashe Stadium in front of a buoyant, raucous crowd. Neither player showed signs of nerves in their pre-match interviews.
Both players traded breaks in the opening three games that lasted 25 minutes. The match then settled down, with serves held with reasonable comfort. Both were hitting the ball exceptionally clean and hard, but Raducanu was making less errors and looked most likely to strike for the set. And a 5-4 up, she did just that, a backhand winner off a Fernandez second serve setting up a set point. Fernandez battled back to deuce but Raducanu chiselled out another two set points and, at her fourth attempt, took it. She was one set away from the US Open title.
All the momentum was with Raducanu, but Fernandez clung on. She held from 0-40 down in her first service game in a bid to turn the tide, and the crowd responded, willing her to fight back. In the very next game, she broke Raducanu to hold a slim advantage. It didn't last long, though, as Raducanu broke back immediately and then held for 3-2.
Now it was time for Raducanu to turn the screw and she did so, breaking for a 4-2 lead with a remarkable passing forehand and then consolidating for a 5-2 lead. She was now one game away from the US Open title.
Raducanu had shown no signs of the nerves that blighted her last-16 match at Wimbledon when she retired with breathing difficulties. Given what she was on the cusp of achieving, she could have been forgiven for feeling the occasion. It did get nervy, Fernandez saving two match points on her serve and then, in an extraordinary denouement, Raducanu needed a medical time-out at 30-40 down after cutting her left leg when sliding to retrieve a ball, much to the chagrin of Fernandez. But Raducanu saw off the danger, and claimed the title with an ace on her third championship point. We have a new British sporting hero, a new Queen of New York City.