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...
Jenny Jones - A singing barlady who had previously overcome meningitis, she sang 'Mercy', much to Will.i.am's and Danny's delight. She opted to go with Will.i.am, but their battle raised the question of which panellist was following whom, when it came to making their team choices.
Teenagers India and Pixie - An incredibly sweet pair, they said no one liked them so they had to stick together, and they couldn't imagine how anyone does this on their own. All four judges wanted them on board, they opted for Jessie's influence. All pictures: BBC
John James Newman - brother's in Waterloo Road, father's in Marmalade... after his rendition of Don't Worry Be Happy, Danny's his coach now.
Sophie Griffin - From Northern Ireland, seemed more anxious about impressing her hero Danny O'Donoghue than getting through with her rendition of American Boy, a song whose original version was produced by Will.i.am. "I've queued for hours to see you, and here you are front for me," she told Danny. "I love you so much, I think you're amazing... wow" ... It wasn't Danny who turned round, though, but Will.i.am.
Ben Lake - Got his (first) big break on Jerry Springer The Opera. Channelled his inner Shirley Bassey to belt out a theatrical version of I Who Have Nothing, but sadly nothing that impressed the coaches. "I thought you were a female to start with" said Jessie. He appreciated the warmth of the audience, though, and said he'd keep going.
Emmy J Mac - Children's dance instructor, sang Put Your Record On. Although Will.i.am and Tom both wanted her, she opted to go with Danny, after a strange Cilla Black 'Blind Date' round-up from Jessie.
Harriet Whitehead - The hippy in her class, she belted out The Non Blondes' What's Up like her life depended on it, but the chairs stayed still. Danny was tempted, but he told the others, "I already have one like her."
Jaz Ellington - He's going to take some beating, after the performance he gave moved the judges to tears.
Lindsey Butler - Said The Voice was the first thing she thought about in the morning, and the last thing at night. Tom Jones responded to the Elkie Brooks-like lilt in her voice on I Don't Walk To Talk About It, and she was on board.
Ruth Brown - Choir singer from London, with a big-voiced rendition of When Love Takes Over. Ruth had previously explained how she was singing for her father who died only a few months ago, and Tom was sufficiently moved to bang the button as she hit her big note.