Written by and starring the talent show's judge David Walliams, the show follows the relationship of teachers in a secondary school.
Catherine Tate and Philip Glenister also star in the sitcom, which last aired in August 2013.
Carroll, who was a runner-up in the last series of Britain's Got Talent, will play Dean, a new boy at Greybridge School.
The comedian, who suffers from cerebral palsy, will see his character taken under the wing of Tate's character Miss Postern.
Walliams told The Sun: "I am excited to be welcoming so many talented new faces to the show - and it's great to be working with Jack."
Former Holby City star Jimmy Akingbola is another new addition to the cast. He will play hunky teacher Mr Dalton and is set to get the pulses racing among the female teachers.
Charlotte Moore - Controller of BBC One - announced that the show would be getting a second series last year.
She said at the time: "I loved the fact that we were in a new precinct and environment, with a stellar cast."
Watch Jack Carroll on Britain's Got Talent below: