Hampshire County Council has given the green light to the spending of £964,000 to overhaul Wyvern College in Botley Road, Fair Oak.
Although planning permission has not yet been granted, the approval of funding is a significant step towards the work taking place.
Work will take place both inside and outside the school, with bosses hoping to construct a new media suite, a new drama studio and partitioning to improve acoustics throughout the school.
Outside, there are proposals for new secure fencing, external lockers, automated intercom gates and nine relocated parking spaces.
It is hoped that these external changes - which will secure the current school frontage, which is currently open to the public - will improve child safeguarding, with the interior redevelopment creating a better learning environment.
Felicity Roe, director of culture, communities and business services, said: 'The reconfiguration of three internal teaching spaces, both specialist and general teaching, will improve the current provision and create a more useful and accessible accommodation layout together with the provision of additional lockers throughout the campus.
'Wyvern College together with the adjacent Fair Oak Infant and Fair Oak Junior Schools will remain in use during the construction period and local management arrangements will be put in place to manage the health and safety during the construction period on site.'
Wyvern College currently has 1,301 pupils enrolled.
There are no plans to increase the number of pupils at the school, according to the county council's report.
Previous approvals were sought by the school for the addition of an all-weather pitch and ICT equipment, totalling £1.1m.
Wyvern College will be paying for the redevelopment in full, meaning no extra money will be spent by the county council.
However, the school still needs the thumbs up from the council to make the investment.
Speaking at her recent decision day, the county council's executive lead member for children's services, Cllr Roz Chadd, said she was 'happy' to approve the spending.
'It's great that we're able to do this,' she said.
The plans are expected to go before the regulatory committee next month.