The 16 year old school boy from Surrey started playing piano aged 7 and has been busking since the age of 13.
At the auditions, he said his dad, who works overseas 9 months of the year, is his biggest fan but couldn't attend the audition.
However Reuben got a shock when his dad popped up in the audience to surprise him.
"He's gone to bits," said Amanda Holden as Reuben was left emotional by the sight of his father in the crowd.
Reuben went on to perform his own song called Lifeline, explaining it was an apology song to his girlfriend who previously dumped him.
Reuben got four yeses from the panel with Simon Cowell saying: "Good for you. That was a great audition Ruben, you've come on and been authentic, be original. I really, really like the song, You've got talent."
David Walliams added: "What a talented young man you are. Incredible to write such a beautiful song at your tender age to sing it so beautifully."
And Alesha Dixon said: "I've so much admiration for you, you're up there bearing your heart and soul and that makes you really vulnerable... I'm sure your dad was proud."
Lifeline is far from Reuben's only song, with his YouTube page showcasing a number of self-penned tracks uploaded over the past year.
Despite being performed on BGT - where his audition has been watched over 2 million times now - Lifeline isn't Reuben's most popular track.
Instead, that title goes to White Dress which Reuben first posted online in October last year.
Another song proving popular online is Cigarettes, which Reuben says is "about a girl who's gone off the rails." You can watch even more of Reuben's songs on his YouTube page.
Britain’s Got Talent 2017 continues tonight at 7:30PM with the live semi-finals.
Reuben will be performing a bid to make the live final on Saturday night.