During the crossover after 8pm when the two shows were shown simultaneously for 20 minutes, an average of 11.8 million viewers tuned into the BBC1 talent show, with just 5.8 million watching BGT.
The figures come after ITV bosses backed down by shifting BGT to a later viewing slot to avoid a further head-to-head clash with the rival show.
ITV1 will screen Simon Cowell's talent contest at 8.30pm on April 21 - half an hour later than previous shows in this series.
However, ITV chiefs took comfort when BGT took its highest peak audience of the series.
A total of 12.2 million tuned into the show last night - 12.9 million including the channel's +1 strand.
It was the highest of the night with The Voice taking a peak audience of 12.1 million.
During Saturday night's BGT one group bidding for fame got an extra member when judge David Walliams joined them on stage.
The comic, who is a panellist on the show alongside Simon Cowell, Alesha Dixon and Amanda Holden, teamed up with the five-piece Show Bears for their own unique take on The Weather Girls' It's Raining Men.
Meanwhile, coaches in The Voice - Jessie J, Tom Jones, Will.i.am and Danny O'Donoghue - finalised the line-up of their teams.
Meet this week's Voice contestants, with an update on their progress beneath...