The funding, totalling £763,000, will come from the council’s Basic Need and School Condition funding and go to Ormiston Sandwell Community Academy. in Oldbury.
It will allow for the conversion of two classrooms to an additional science laboratory and the extension of the existing dining space.
Additional toilets will also be introduced across the school to ensure 60 are provided in total.
Speaking at Sandwell Council's cabinet meeting, Councillor Ann Shackleton asked whether the Ormiston Academy Trust, which the school belongs to, will be putting money towards the refurbishment.
She said: "Will the trust be putting money towards this project, or have I missed it? As in the long term it is the academy which will benefit from it."
Councillor Karen Simms moved to point out the local authority has a statutory duty to ensure a sufficient supply of school places.
The cabinet report also explains how an unprecedented growth in the birth rate, which has resulted in a high demand for school places, has now started to ease.
Councillor Simms said: "This is an authority expansion and the council is responsible for funding new places.
"The local authority funding will focus on the main internal works, while the trust plans to remodel the external area.
"The trust are aware that the additional pupils will bring additional footfall and vehicle movement."
Ormiston Academy Trust has proposed to fund works to increase parking provision, allowing the existing car park to operate as a safe pick-up and drop-off zone.
It is hoped this work will minimise congestion on Lower City Road and neighbouring roads