The Office for the School Adjudicator examined the proposals to merge St Nicholas in Chippenham, Larkrise in Trowbridge and Rowdeford in Devizes and establish the new, maintained special school with a single leadership team to work across the schools.
The move will see more places created across north Wiltshire.
In a letter to parents, Larkrise headteacher Phil Cook said: “This means that on August 31, Larkrise, Rowdeford and St Nicholas will technically close as three separate schools, and on September 1, 2020 a new single school will be created on the three existing sites.
“This decision is an important milestone and reflects a lot of hard work from all the governors, staff and the wider school communities.”
After consulting with parents, pupils and schools, Wiltshire council approved a number of recommendations including maintaining the schools under amalgamated leadership and expanding Rowdeford school to accommodate 400 additional pupils as part of the new school.
Cllr Pauline Church, cabinet member for children, education and skills said: “The OSA decision is an important step in securing the very best provision for our SEND pupils for the future.
“In preparation for this decision we have already started to design a build programme to meet the need for additional special schools places in north Wiltshire.
“Although Covid-19 has created some challenges, I look forward to continuing that working together with families, pupils and schools so we have the best available provision which meets the needs of our SEND pupils now and in the future.
“The three schools have been doing excellent work planning for the future, and we look forward to continuing to work with the new school on this exciting project.”