The group are made up of 14-year-old Jacob, 15-year-old Noah, 15-year-old Tom and 15-year-old Jake and got Amanda Holden's golden buzzer on Saturday.
They performed a medley of hits by Stevie Wonder and sailed straight through to the live shows.
Amanda said: "I think you are absolutely incredible and now you've just got to win the whole show."
The group met while performing in London's West End in School Of Rock The Musical and say their stage experience helped their audition.
Appearing on ITV's This Morning, Tom said: "I used to find it hard to sing and play guitar at the same time. I just didn’t understand how people could do it. I think School Of Rock helped us a lot....
"In School Of Rock you get used to going on stage so it’s weird to become nervous. I’m sure all of us got nerves before the first show of School Of Rock, panicking and stuff."
The four piece went on to reveal how the group began, with Noah explaining: "Me and Tom shared a room because we live up north and couldn’t commute every day to the theatre.
"We had a music room in the house and we’d sneak in there and practice gigs and get told off a lot."
He added: "We had only played once as a band before Britain’s Got Talent in front of our mums, so we didn’t know what it was like."
Following their BGT success, Tom said the group had big dreams for the future.
"We dream about playing the 02 and Manchester Arena and stuff like that," he enthused.
Following Saturday's show, Chapter 13 have lept to the head of the Britain's Got Talent betting at 6-1 with Star Sports, after their performance earned them a bye to the Live shows thanks to the golden buzzer.
Former favourites, Dave and Finn are 7-1, with David Walliams' golden buzzer Flakefleet School Choir at 8-1.
Britain's Got Talent 2019 continues this Saturday night on ITV with the latest auditions.
The live semi-finals take place later this year.