The double A-side of 'Anything Is Possible' / 'Evergreen', which reached number one after Young won the talent show in February 2002, sold a total of 1.8 million units, the Official Charts Company revealed today.
Young's Pop Idol runner-up, Gareth Gates, released the decade's second-biggest seller, shifting 1.3 million copies of 'Unchained Melody', the single that knocked 'Anything Is Possible' / 'Evergreen' off the top spot three weeks later.
Tony Christie's Peter Kay-assisted version of '(Is This The Way To) Amarillo', released in aid of Comic Relief in 2005, was the third-biggest seller, while Shaggy and Rikrok's 2001 chart-topper 'It Wasn't Me' was fourth.
Meanwhile, number ones by Kylie Minogue, Hear'Say and X Factor champions Alexandra Burke and Shayne Ward also charted in the top ten, alongside charity releases from Band Aid 20 and Bob The Builder.
The top ten singles of the noughties in full:
1. Will Young: 'Anything Is Possible' / 'Evergreen'
2. Gareth Gates: 'Unchained Melody'
3. Tony Christie ft. Peter Kay: '(Is This The Way To) Amarillo'
4. Shaggy ft. Rikrok: 'It Wasn't Me'
5. Alexandra Burke: 'Hallelujah'
6. Band Aid 20: 'Do They Know It's Christmas?'
7. Kylie Minogue: 'Can't Get You Out Of My Head'
8. Shayne Ward: 'That's My Goal'
9. Hear'Say: 'Pure And Simple'
10. Bob The Builder: 'Can We Fix It?'