Tao Geoghegan Hart became only the second British man to win the Giro d’Italia as he took the title in Milan.
The 25-year-old, who won stage 20, was tied with Australian Jai Hindley before the final stage, the first such instance in the race’s history.
But Ineos Grenadiers’ Geoghegan Hart finished 39 seconds ahead of Hindley in the 15.7km time trial.
“Not in my wildest dreams did I imagine this would be possible when we started,” said Geoghegan Hart.
“It’s incredible, really incredible.”
Chris Froome is the only other British man to win the Giro, in 2018.
Geoghegan Hart is the fifth British man – alongside Froome, Bradley Wiggins, Geraint Thomas and Simon Yates – to win a Grand Tour.
In only his fourth Grand Tour, Geoghegan Hart began the race as one of Geraint Thomas’ domestiques and was in 126th place after the opening stage.
Geoghegan Hart described his victory as “bizarre”, adding: “All of my career I’ve dreamed of trying to be top 10 – top five maybe – in a race of this stature, so this is something completely and utterly different to that and it’s going to take a long time to sink in.
“My DS (director sportif) told me I was 10 seconds up and then he kept giving me a few seconds. I only knew we must be in a pretty good situation when they were screaming not to take any risks in the last kilometre.
“It’s not often your DS tells you to slow down that much in a 15k TT, but I also knew the work was done up to that point so it’s incredible to arrive here.
“I’m just going to enjoy this. I’m going to stay the same person, stay as professional as I believe I always have been, dedicated, waking up every day looking forward to riding my bike, loving my life and being grateful for the amazing honour and privilege I am in on this team at these beautiful races.”
In 11 years of racing, Ineos Grenadiers – formerly known as Team Ineos and Team Sky – celebrated their most successful Grand Tour with seven stage wins.
Ineos’ Filippo Ganna won the final time trial by 32 seconds, his fourth stage win of the race. Geoghegan Hart was 13th, 58 seconds behind.