BBC One's flagship entertainment show managed a peak of 11.3m (46%), and averaged 9.91m (43.5%) between 6.30pm and 8.30pm.
Despite airing later in a more lucrative slot, The X Factor could only score an average of 8.68m (36.2%) from 8.20pm, peaking with 9.9m (39%) midway through its second live show.
Many believed that the fallout from Carolynne Poole's controversial exit last Sunday would either send The X Factor's ratings soaring or into decline, but the show pulled in exactly the same audience as last week.
While The X Factor added 331k (1.7%) on ITV1 +1 and is repeated again today, initial overnight figures show that Strictly beat its rival by its biggest margin since 2006.
Elsewhere, Merlin rallied to 5.59m (22.3%) at the later-than-usual time of 8.30pm, after which 3.87m (16%) watched the latest Casualty, and the postponed final episode of drama Good Cop drew 1.94m (12.4%) at 10.30pm.
Meanwhile, The Jonathan Ross Show interested 2.96m (19.3%) on ITV1 (+1: 160k/1.8%), and The Xtra Factor entertained 541k (3.5%) on ITV2.
BBC Two's penultimate airing of The Thick of It attracted 893k (3.7%) at 9.30pm, while live boxing nabbed 1.06m (6.7%) on Channel 5 and The Million Pound Drop Live took 818k (3.3%) for Channel 4 (+1: 113k/0.5%).
Overall, ITV1 secured the most marginal of Saturday night victories over BBC One, with 27.3% versus 27.2%. Far away in third place, BBC Two had 4.5%, while Channel 4 and Channel 5 each had 3.2%.
BARB ratings data supplied by Attentional