The BBC reports that Primark's owner Associated British Foods (ABF) said like-for-like sales at, which excludes new store openings, rose by 3% in the year to 15 September.
Total sales increased by 15%, helped by 19 new branch launches.
ABF, which also owns Silver Spoon sugar, said its annual profits would be "substantially ahead" of a year ago.
It releases its full annual results on 6 November.
ABF said profits at Primark would have been higher still if it were not for high cotton prices in the first half of its financial year, a cost it chose "not to pass onto customers".
The 19 new stores brought the total number of Primark outlets across the UK and Europe up to 242.
A second large store on London's Oxford Street is due to open at the end of this month.
At ABF's sugar business, full-year profits will be "considerably higher" than a year earlier, led by strong sales in Europe and Africa.
However, profits at the group's grocery division will be lower, due to restructuring costs at its George Weston Foods business in Australia, which has faced increased competition.