ITV said the programme was the highest rating show of the year so far, nudging ahead of a Coronation Street which pulled in 11.2 million in January.
Adding viewers for ITV's +1 channel brought the audience to 11.9 million for the BGT finale, with a peak audience of 14.5 million.
More top news
More than 200 guns were handed in to police during a regional gun amnesty this month.
Simon's Blog - Sunrises & Sunsets
Wednesday night's weather for the west of the region