The 10pm show, which saw Reid triumph as the winner over Dane Bowers, attracted 4.04m (19.8%) to Channel 4, with a further 272k (2.2%) tuning in on timeshift.
The figure topped Ulrika Johnson's victory last year, which pulled in 3.48m (17.9%) on Friday, January 23, 2009.
The first results show of the evening managed 3.61m (14.2%) between 8.30pm and 9.30pm. 191k (0.8%) watched on Channel 4+1.
Sandwiched between the two visits to BB, 8 out of 10 Cats logged 3.05m (12.2%).
Over on BBC One, QI put in 4.32m (17.1%) at 8.30pm, then Silent Witness drew 6.14m (24.2%) during the 9pm hour.
Mastermind and An Island Parish grabbed 2.3m (9.6%) and 1.82m (7.2%) for BBC Two during the 8pm hour, then 1.91m (7.5%) watched Empire of the Seas at 9pm.
Five's Monster Python averaged 603k (2.5%) at 8pm, then 1.09m (4.9%) tuned in for The Siege between 9pm and 11.15pm.
Overall, BBC One edged primetime with an average share of 22.3% to ITV1's 21.7%. Channel 4 was third with 11.9% (+1: 0.8%), followed by BBC Two with 7.1% and Five's 3.1%.
BARB ratings data supplied by Attentional