Phillip Lawrence was killed in front of his pupils at the gates of St Georges School in Maida Vale, West London, in 1995, which Tokio said pushed him into music.
“There was a tragic time,” he told hosts Ranvir Singh and Charlotte Hawkins. “It’s something I don’t wish to talk about too much, because I don’t want to bring it back too much for the family.
“But I had music to really channel my energy and stay on a positive path.
“I’ve worked and worked and worked so hard to get to this point.”
He continued: “I feel very, very lucky to be in a position to have turned my life around, and hopefully have inspired people who are going through the same things that I’ve been though that we are here together and we can do this.”
Tokio blew judges Simon Cowell, 57, Amanda Holden, 46, David Walliams, 45, Alesha Dixon, 38, with a spell-bounding piano recital of a Debussy piece mashed up with Ed Sheeran.
After leaving school, Tokio went on to play as part of the band Mr Hudson and the Library, who supported the likes of Amy Winehouse and Kanye West.
Also on last week’s Britain’s Got Talent,Amanda used her golden buzzer on Malawi comedian Daliso Chaponda.
What’s more, the ITV talent show was stung with more controversy over claims magician Issy Simpson stole her trick, which became the talk of the town last week.
Fellow magician Carl Leek – known by his stage name The Starman – claimed the eight-year-old “stole” her trick, claiming that he felt “sick” watching Simpson’s audition.
Britain’s Got Talent continues Saturday at 8pm on ITV.