Airing at 8.25pm, the relaunched talent show - now in its fifth series - appealed to 9.94m (40.6%) on ITV1, attracting a peak of 10.45m (42%) in the final 15 minutes, and adding 495k on +1.
However, last night's premiere was slightly lower than the equivalent launches in 2010 and 2009.
Immediately following Britain's Got Talent, spinoff show Britain's Got More Talent - presented by Stephen Mulhern - mustered 877k (4.2%) from 9.50pm and 219k on ITV2 +1.
In a bumper night for ITV, Keith Lemon and Stacey Solomon's new format Sing If You Can opened with a respectable 5.19m (25.5%) at 7.25pm and 136k on ITV1 +1, Piers Morgan's Life Stories with Russell Brand interested 4.13m (20%) alongside a further 249k on +1 at 9.50pm, and the much-hyped Manchester derby FA Cup semi-final scored 6.38m (37.7%) from 4.45pm, peaking with 9.58m (47.9%) in the game's final 15 minutes.
Over on BBC One, Eurovision: Your Country Needs You got off to a dismal start, with 2.01m (10.5%) between 6.10pm and 7.10pm, then 3.63m (18%) watched a live So You Think You Can Dance and The National Lottery: Secret Fortune slipped to 3.71m (15.7%) at 8.10pm.
'A Real Shame' in Casualty logged 4.21m (19.9%) at 9pm, before a Live at the Apollo repeat amused 3.12m (14.3%).
Elsewhere, BBC Two's tribute documentary to Elizabeth Taylor pulled in 2m (8.9%) at 8pm and 1.12m (4.5%) tuned in for Timeshift: In Shackleton's Footsteps, while Channel 4's screening of The Day After Tomorrow entertained 1.48m (6.3%) and 303k on +1.
Meanwhile, CSI: NY delivered 1.7m (8.1%) to Channel 5 from 9.50pm, the broadcaster's best audience by far.
Predictably, ITV1 stormed primetime with 31.7% (+1: 1.3%), ahead of BBC One's 16.3%, BBC Two's 5.8%, Channel 4's 5.7% (+1: 1%), and Channel 5's 4.5%.
BARB ratings data supplied by Attentional