The 13-year-old from Widnes, who hopes to record her own music one day, sang Defying Gravity from the musical Wicked and won a standing ovation from everyone in the audience.
Beau overcame her nerves on Saturday night and impressed Holden and fellow panellists Simon Cowell, Alesha Dixon and David Walliams.
After Holden hit her Golden Buzzer, which gives Beau an automatic place in the live shows, she headed to the stage and embraced the schoolgirl.
Cowell said: "I like the way you came up here and just mugged all of us like, 'Yeah, I'm really nervous'. But that's how you do it."
Dixon added: "You are fantastic."
"Everyone else might as well just go home," Walliams joked.
"That is one of the most difficult songs, I think, to sing. And you just sold it to us," Holden said as Beau left with four yeses.
The panel are again casting a discerning eye over acts including singers, dancers and performing animals in a bid to find a new star.
Presenters Ant and Dec are on hand to encourage the acts battling for the opportunity to appear at the Royal Variety Performance.
The show may be called Britain's Got Talent (BGT), but that has not stopped the flow of performers from outside the UK.
The judges visibly winced and covered their eyes as they watched Alexandr Magala pass a sword through his mouth.
The 26-year-old from Moldova performed what has been described as "one of the most dangerous acts ever" on the hit ITV show.
At the climax of his performance, Magala slid down a pole upside-down with the sword lodged in his mouth, and came to a stop inches above the stage floor.
It left Ant and Dec and the panel speechless.
"I was just relieved you were still alive at the end of it," Walliams said.
"I actually thought you were going to die," Cowell admitted as the Moldovan secured four yeses.
Musician Vitaly Voronko, from Belarus, walked away with three yeses and is also into the next round.
The Togni Brothers, Dario and Michael, aged 19 and 20, are foot jugglers from Birmingham. Raised in a circus in Italy, their act saw one sibling flip the other in the air using his feet.
Cowell said he had "never seen anything like it" as the siblings took home four yeses.
The first show of the new series, which is celebrating its 10th anniversary, turned the spotlight on talent even younger than the Tognis.
Paisley Kerswell, an 11-year-old breakdancer from Merseyside, and George Kavanagh, a self-assured 11-year-old comedian from Grimsby, were both awarded four yeses.
Throughout their audition to Queen's Don't Stop Me Now, members of the Collaborative Orchestra and Singers popped up from all around the arena.
"I've worked out that if you win, you're going to make about 8p each," Cowell said as they played their way to four yeses.
Voiceover artist Darren Altman, 43, won over the judges with his range of impressions which included London mayor Boris Johnson as well as Ant and Dec.
"A lot of those impressions, I've never heard people do before," Walliams said as Altman secured four yeses.
Also winning four yeses were streetdancers Elite Squad Royalz and dancing dog act Lucy And Trip Hazard.
:: Britain's Got Talent continues next Saturday on ITV.