The magician asked 52 members of the live audience to think of an object and write the word down on a piece of paper. He then asked Alesha Dixon to shout 'stop' as he shuffled the pack of answers, before giving each judge a word.
Jamie proceeded to conjure up the objects from nothing - a goldfish for David Walliams, an ice cube for Alesha, a shoe for Simon Cowell and a helicopter for Amanda Holden (yes, really).
However, some viewers began pointing out flaws in Jamie's trick, noting that he had taken off his shoe before Simon had said the word so must have known what it was beforehand. The most beady-eyed Twitter users took screenshots of Jamie slipping off his shoe while working on Alesha's ice. The cameraman and your TV's rewind button have a lot to answer for. So does the person in the audience who wrote 'helicopter' but failed to make themselves known when asked by Simon.
How do you think Jamie Raven conjured up a goldfish and a helicopter? Answer - He knew what was coming. Not magic, pure bluster #BGT— James Way (@JimboWay6) May 27, 2015
Personally I think @Kingdomtenors should replace Jamie Raven.. Nobody admitted to writing helicopter and he already had his shoe off..— Tyler Bowie ￼ (@tylerbowiex) May 28, 2015
So happy Jamie Raven won that semi final, even though after the whole helicopter card situation I'm not sure i believe anymore #bgt— misslindseytay (@Lindseytaylor__) May 27, 2015
"Who wrote helicopter?" Er, well, Jamie Raven, then he forced 4 cards to you all. By going large, he made it more obvious. :( #bgt— George Stevens (@pompeygeorge) May 27, 2015
Nevertheless, the judges and many other viewers were left open mouthed at Jamie's performance, with Alesha saying she was "absolutely gobsmacked".
That Jamie Raven off bgt has baffled me— Dale Wilson (@bcfc_dale) May 28, 2015
In his first audition, Jamie turned four £50 notes into 'Bank of Britain's Got Talent' notes complete with the judges faces drawn onto them. The trick got even more mind-boggling before Simon declared that he "actually believes in magic" - quite a feat.
Britain's Got Talent 2015 finalists
Britain's Got Talent 2015 finalists
Jules and Matisse wowed the Britain's Got Talent crowd with their comedy dog routines to go on and win Britain's Got Talent 2015
2/10 Calum Scott
Calum Scott was Simon Cowell's Golden Buzzer act earlier in the series and has performed 'Dancing on My Own' and 'We Don't Have To Take Our Clothes Off' so far
3/10 Old Men Grooving
Old Men Grooving are showing Britain's Got Talent that dad-dancing is definitely back in - they went through based on the public vote after the judges' votes were tied
Light dance group UDI offer something 'unique' to Britain's Got Talent - they went through based on the public vote after the judges' votes were tied
5/10 Danny Posthill
Danny Posthill will be hoping his funny impressions of the rich and famous bag him the grand Britain's Got Talent prize
6/10 Jamie Raven
The Britain's Got Talent judges watch contestant Jamie Raven turn fire into ice during a live semi final - he won the public vote
7/10 Isaac Waddington
Isaac Waddington performs in the Britain's Got Talent semi-final to win the public vote and guarantee a spot in the final
8/10 The Neales
Family vocal group The Neales moved Simon Cowell to tears with their semi-final performance of 'Father and Son' to win the judges vote and go through to the final
9/10 Cor Glanaethwy
Welsh choir Cor Glanaethwy perform on Britain's Got Talent before winning the public vote to make it through to the grand final
10/10 Entity Allstars
Alesha Dixon pressed her Golden Buzzer for dance group Entity Allstars and they later progressed into the final courtesy of the judges
Jamie will compete for a £250,000 cash prize and a slot on the line-up of the Royal Variety Performance during Sunday night's nail-biting climax.
Catch all the action live on ITV from 7.30-10pm.