Last year, the return of creator Simon Cowell as a judge on the ITV show helped boost the ratings for the season debut.
The 12th season-launch episode, however, drew an average 7.7 million viewers, down from 9.5 million viewers last season, said The Hollywood Reporter.
The second episode of the new season also drew lower ratings than last year, attracting 6.5 million viewers, down from 8.2 million last year.
The 2013 season premiere had attracted 9.2 million average viewers in the overnight ratings, up from 8.7 million in 2012, which had been the show's lowest figure since 2006, when the season opener drew 7 million viewers.