The figure is a triumph for Richard Desmond, proprietor of Express Newspapers, which also owns the Daily and Sunday Express, not least because it is over 100,000 copies more than its daily title's most recent ABC figure of 753,927.
Desmond said he was "proud and delighted" with the paper's debut.
In a statement, Desmond said: "The first week's sales figures for the Daily Star Sunday show the power of the Daily Star brand. They also demonstrate the genuine demand that existed among readers for the new newspaper on Sunday."
The Daily Star Sunday had been widely expected to sell around 400,000 copies, made up of Daily Star readers and those picked up from rival titles. Around 300,000 to 400,000 Daily Star readers are estimated not to buy a Sunday paper and it is thought that Desmond only needed to sell around 400,000 copies to break even.
Analysts have predicted that the Daily Star Sunday will chip away at the circulation of Trinity Mirror's standalone Sunday newspaper The People, which has just undergone a £2m relaunch, as well as hitting the Sunday Mirror.
The People recorded an average UK circulation of 1,341,825 in August, however, all eyes will be on its September figure to see if its share has been eroded by the new launch.
The Daily Star Sunday launched with a knock-down cover price of 35p, almost half that of its 65p rivals in the tabloid market. None of its rivals moved to match the cover price, possibly because Sunday Mirror and People publisher Trinity Mirror has already shelled out in a price war with The Sun, while the News of the World was confident that it would lose few readers.
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