The X Factor winner's cover of the Shontelle track is the fastest-selling single of 2012, shifting over 490,000 copies. It is also the second fastest-selling track by an X Factor winner after Alexandra Burke's 'Hallelujah'.
Speaking of his first number one single, he said: "To everyone from home and around Britain who bought the single, thank you very, very much.
"You've made my dreams come true. The fact that it was in aid of Together For Short Lives, which is a great cause and a great charity, I think that really helped.
"My number one award is going to go on my mantelpiece, and I'll probably kiss it for two weeks solid every time I pass it!"
'Impossible' has also outsold 2011 winners Little Mix's debut 'Cannonball' by over two copies to one, after they sold 210,000 in their first week.
will.i.am and Britney Spears land at two with their collaboration 'Scream & Shout'. The track is Spears's 22nd single to reach the UK Top 10.
Bruno Mars falls one place to three with 'Locked Out of Heaven', while Gabrielle Aplin's 'The Power of Love' drops three from last week's summit to four. Olly Murs rounds out the top five, with 'Troublemaker' falling two spots.
Rihanna scores yet another Top 10 hit with 'Stay' at six, while former number one 'Diamonds' is at seven.
Labrinth drops four to eight with 'Beneath Your Beautiful'. Psy is a non-mover at nine with 'Gangnam Style', with One Direction falling four to ten with 'Little Things'.
Taylor Swift climbs two places to 11 with 'I Knew You Were Trouble'. One Direction enter at 12 with their latest single 'Kiss You'.
Shontelle's original version of 'Impossible' re-enters at 22, followings its original peak of nine in 2010.
Daley enters at 24 with his Jessie J collaboration 'Remember Me'. Emeli Sandé grabs another top 40 hit at 35 with 'Clown', while there are re-entries for Ellie Goulding's 'Anything Could Happen' and McFly's 'Loving Is Easy' at 36 and 37.
Watch the video for James Arthur's 'Impossible' below:
Source: Official Charts Company
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