Charlotte Moore - Controller of BBC One - made the announcement today (December 2) at a BAFTA session.
"We've recommissioned Big School," she said. "I loved the fact that we were in a new precinct and environment, with a stellar cast."
Moore also claimed that Big School could have a "long" run, with more series in the planning stages.
BBC One has also ordered a third series of its comedy Citizen Khan, plus new sitcom Grey Mates starring Russ Abbot.
Big School was co-created by David Walliams and stars the comic as bumbling chemistry teacher Mr Church.
Catherine Tate and Philip Glenister also featured in the first six-part series, which aired on BBC One between August and September.
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Watch a deleted scene from Big School below: