Parents and teachers of pupils at Vale of Berkeley College in Gloucestershire say they are devastated to have lost the fight to save it from closure.
A campaign to keep the school open as a co-operative trust began last year after it was rec ommended for closure.
But the county council said pupil numbers were too low for it to be cost-effective.
Headteacher Nicola Ross said pupils were "shocked and stunned" by the news.
Parent Claire Peppard said: "We were devastated. That's the reaction of the whole community.
"The children are going to lose all their friendships and have to settle again."