Teachers at Thomas Bennett Community College have voted "overwhelmingly" for strike action, the National Education Union has confirmed.
NEU members were balloted after The Kemnal Academies Trust (TKAT), which runs the school, announced a "restructure" which would see £987k cut from the budget.
The union said the cuts would see at least 22 teachers and support staff lose their jobs, with "drastic" funding cuts to areas such as support for children with special educational needs.
A spokesman said the vote saw 99 per cent in favour of strike action, with a turnout of 89 per cent.
Paul McLaughlin, NEU regional secretary, said: "This overwhelming result shows the enormous strength of feeling that members have over this devastating issue.
"We’re calling on the employer to come to the table with serious plans to save this school, otherwise we will be forced to take significant action.”
The union has confirmed that any action taken would not disrupt pupils' exams.
English teacher Alex Ramiz said: “Through this ballot result our members are sending a clear message to The Kemnal Academies Trust that they do not accept their outrageous proposals for running our school into the ground.
"They will take strike action unless TKAT come up with a more workable solution.”
Angela Newman, of the Crawley Community Action Group, a parent-led body formed to help fight the cuts, said: "I am one of the many parents who are concerned about Thomas Bennett and are determined to save the school.
"I want to speak up to say that we fully support the teachers who have balloted for action.
"It’s a shame that it has to get to this but, like us parents they are motivated only to save our school and to be able to provide the children with the education they deserve.”
Following last week's public meeting, which was attended by 150 parents, staff and pupils, a TKAT spokesman said the trust was "disappointed" that staff would be balloted, adding: "The consultation process we are currently in means maintaining an open dialogue to decide on the best way forward for the school.”
Following the meeting, Peter Lamb, leader of Crawley Borough Council, suggested Thomas Bennett should be returned to the control of West Sussex County Council
He said: "When it comes to making ends meet, parents expect schools to put frontline services first.
"TKAT needs to deliver on that expectation or the Department for Education should strip them of the franchise and hand back control of the school to the local community.”
A county council spokesman said Deborah Myers, director of education and skills had raised concerns with both TKAT and the Regional Schools Commissioner.
She added: “Giving children the best start in life is one of our top priorities so we are working to fully understand how any changes to the school will impact upon children’s learning and educational experience, as well as that of staff employed by the academy trust.
“As Thomas Bennett Community College is an academy all decisions on its future are made by the academy trust in agreement with the Regional Schools Commissioner.
“Our lack of jurisdiction in this situation and many others relating to academies and free schools is one of the reasons we argued against the government’s plans to make all schools academies.”
A spokesperson for TKAT said: “We are still in consultation with the NEU on the outcome of the restructure at Thomas Bennett, and will seek to minimise disruption to the school as much as possible once we know the nature of the strike action. We will also ensure parents are kept informed at every stage.”