The purpose-built school - Bohunt Horsham - will provide places for 1,620 pupils aged from 4-16 and include a nursery for 50 young children.
It is being built as part of a new 2,750-home estate on land off Rusper Road, north of Horsham.
It had been hoped to open the new school last year but delays were faced due, in part, to the Covid-19 pandemic.
But plans are gearing up and the brand new school building has now been officially named at a special ceremony attended by senior representatives from government, construction and the Bohunt Education Trust.
Bohunt Horsham - in temporary premises in Hurst Road - opened its doors to 120 Year 7 students in 2019 and, since then, has grown to 440 students across three year groups.
It is set to deliver another 240 secondary school places in September 2022.
The new, purpose built school building will boast state-of-the-art facilities and large playing fields.
When complete, it will provide 1,200 secondary school places, a nursery for 50 young children and 420 primary places.
Bohunt Education Trust leader Neil Strowger and Bohunt Horsham headteacher Georgette Ayling were joined at the official ‘naming ceremony’ by Horsham District Council chairman David Skipp; Horsham MP Jeremy Quin, and divisional director from the Department for Education Paul Mustow, along with around 30 other guests, including architects, engineers and planners - and two of Bohunt Horsham’s founding students.
Council chairman David Skipp said: “The goal of Horsham District Council as part of our Local Plan was to provide a school that not only served the new North Horsham development, but also the existing residents of the town who were in crucial need of school places for their children.
“I hope that this school will continue to accept children from the wider community of Horsham so that as a result of the bridge and other access points, this development will be integrated into Horsham town, and all residents will have the opportunity to enjoy the proposed facilities on offer.”
Trust leader Neil Strowger said: “Our aim is to offer as many young people as possible the opportunity to receive the outstanding education that they deserve, and this building will provide our Horsham students with a truly first-class environment and facilities.
“Thanks must go to the DfE, Wates Group, and the entire Horsham community for their support in the school’s journey so far, and for their tireless commitment to progress.”
Headteacher Georgette Ayling added: “Our students are some of the best young people in the world, embodying BET’s vision and values of enjoy, respect and achieve – whilst developing resilience, curiosity and empathy.
“Any challenges ahead will, I hope, be overcome with students’ safety and education always front of mind.
“I can’t wait to see our amazing young people and staff take residence in the new building, to embark on the next stage of their Bohunt Horsham journey.”
MP Jeremy Quin said: “I am delighted to see the huge progress being made on the new school building. It will be a great asset to our community and I know students and staff are hugely looking forward to completing the move.”
Department for Education spokesman Paul Mustow said: “It is fantastic to see Bohunt Horsham’s new facilities nearing completion, which is a real testament to the many talented people that work across the Free Schools programme.
“The school is already thriving in its temporary accommodation and I’m certain that the move across to the new facilities will enable their pupils to reach their potential, and maybe inspire some budding construction professionals for the future.”
West Sussex County Councillor Nigel Jupp said: “It is an exciting time for the whole school and wider Horsham community that pupils and staff are now so close to moving to their impressive new permanent home.”