A campaign to save Vale of Berkeley College has ended in failure, after the county council deemed it too expensive.
Parents lobbied Gloucestershire County Council after a government report in October last year suggested three schools should be closed.
Central Technology College and Bishop's College in Gloucester will shut at the end of this academic year, to be replaced by an academy.
Vale of Berkeley costs £1,900 more per pupil than the county average.
'Can't afford it'
Governors and parents had hoped to prove the school could become a co-operative trust.
But a cabinet meeting unanimously decided the school would be closed at the end of the 2011 academic year.
Council children's service chief Councillor Paul McClain said: "The educational performance at the school has been poor.
"We cannot afford to keep that school going."