Remarkably, the Channel 5 reality show launched with 2.63m (12%) between 9pm and 10.45pm, exactly the same figure as last year's network launch in September.
A peak at The Auditions saw 1.18m (5.1%) tune in at 8pm, while Big Brother's Bit on the Side with Emma Willis logged 821k (6.9%) from 10.45pm.
Over on BBC One, Silk slipped to 4.73m (19.9%), but still comfortably led the 9pm hour as Martin Clunes: The Lemurs of Madagascar opened with just 1.6m (6.7%) on ITV1.
Rolf Harris's royal return to TV screens in Rolf Paints... The Diamond Jubilee thrilled 4.15m (19.2%) at 6.30pm, after which EastEnders and Holby City both performed well.
Meanwhile, Trash to Treasure (2.89m/13.7%) and Countrywise Jubilee (2.34m/10.2%) aired on ITV at 7.30pm and 8pm respectively.
Elsewhere, BBC Two enjoyed a successful night with good performances from its factual offerings of Great British Menu (2.03m/9%), Springwatch (2.51m/10.9%) and Horizon (2.42m/10.2%).
Channel 4's Embarrassing Bodies: Live at the Clinic fetched 1.59m (6.9%) at 8pm (+1: 352k), then 1.23m (5.2%) watched Jimmy and the Giant Supermarket from 9pm (+1: 178k).
Overall, BBC One topped a one-horse race in primetime with 22.2%, while ITV1 struggled with 11.5% (+1: 0.4%). BBC Two finished an impressive third with 8.7%, ahead of Channel 5's 7.6% (+1: 0.1%), and Channel 4 had 4.7% (+1: 0.9%).
BARB ratings data supplied by Attentional
Photo gallery - Big Brother launch night: