The singer zoomed to the top of the tally after the track's release at midnight, overtaking will.i.am and Britney Spears's new single 'Scream & Shout'.
Meanwhile, this week's Official Chart number one Gabrielle Aplin slips to four with 'The Power of Love', and Ke$ha's 'Die Young' completes the top ten.
Elsewhere, the original version of Arthur's 'Impossible' by Shontelle is at 13, One Direction's 'Kiss You' lands at 14, and Rihanna's 'Stay' is at 15.
Mariah Carey's 'All I Want For Christmas Is You' is at 20, Daley's 'Remember Me' is at 21, and Emeli Sandé's 'Clown' starts at 23.
Arthur recently revealed that his debut album will be released "as quickly as possible", adding: "I'm not gonna wait around. I've got a lot of material ready to go now."
Syco is donating 100% of the profits from each download and CD sale - estimated at £1 per CD and 20p per download - to children's charity Together for Short Lives.
>Read Digital Spy's review of 'Impossible'
Watch James Arthur perform 'Impossible' below: