Carinya Christian School can start building its new senior school in 2020.
The Gunnedah school will receive $900,000 in funding through the state government's Capital Grants Program for the infrastructure project, which has been on the cards since 2018.
It is stage two of the school's expansion program and will include the construction of two general-purpose learning areas, visual arts learning space, covered learning areas for design and technology and learning, works on verandahs and walkways, staff rooms, administration and reception buildings, a sick bay and storage.
The decision to expand was driven by growing enrolments and to provide more options for families.
Parkes MP announced the school's funding success on Friday and said he looked forward "to seeing the positive impact the new infrastructure will have on students and the local community".
School principal Chad Kentwell said the project architect was preparing plans to include in a variation to its development application for the entire project, which was approved by Gunnedah Shire Council in 2018.
Mr Kentwell said they were deviating from the original plans because the school had successfully acquired 44 Elgin Street, which is parallel to the junior school building.
The acquisition will give the school more room for stage three of the project so car parks, more admistration areas and a new library can be included.
Stage three also includes a new or refurbished early learning centre.
If the school is able to purchase 42 Elgin Street, it will repurpose the house as a new early learning centre. The school will apply for Capital Grants Program funding in 2021 to build in 2022.
Mr Kentwell said he hoped the school could go to tender for stage two - the senior school building - in early 2020 to build in mid-2020.
"We're quite thrilled that the department is supporting us in this way, to this extent," he said.
"We're very grateful and it's going to enable us to build an excellent facility.
"In the meantime ... we're also doing other significant refurbishments to the junior school this year, including some more air-conditioning in classrooms, creating some learning support spaces, recarpeting and repainting."
The school build a junior school in Elgin Street in 2018 and introduced year 7 this year. Next year, the school will introduce year 8.