The 19-year-old singer-songwriter was the first act announced to reach the final, having won the viewers' vote following his performance of a self-penned track.
Aquabatique and Billy George were also voted by the public into the top three acts, with the judges' vote given to the synchronised swimming group.
Choosing between the acts, David Walliams went for the swimming team, saying: "They're two quite similar acts, both need incredible strength and endurance. I will choose the act that I thought made the most impact tonight, which is Aquabatique."
Alesha Dixon found it difficult to pick her favourite, eventually saying: "I don't know. I love you both. Both of you bring originality to the show, this is the hardest one yet. I love you both but I'm going to even up the score, Billy."
With Amanda Holden going for Aquabatique, the deciding choice went to Simon Cowell, who said: "Billy, you were absolutely brilliant tonight. You girls lost out on the chance to represent at the Olympics, and you were amazing this evening. The act that I'm going to send through to the final is Aquabatique."
Strictly Wheels, Hope Murphy, Callum Oakley, Martyn Crofts, Greig Stewart and Face Team were also eliminated tonight.
A final wild card act will be chosen by the judges to join the finalists on Saturday.
Britain's Got Talent continues on Saturday (May 12) for the final, airing at 7.30pm on ITV1.
Photo gallery - Britain's Got Talent's fifth semi-final:
Copyright: Rex Features Ken Mckay/Thames