Shrewsbury High School will close its nursery department next summer and relocate its Roman Road prep school to the main buildings in the town centre as part of moves to focus mainly on the education of girls.
The school which is part of the Girls' School Day Trust currently operates at premises in Town Walls and Roman Road and also has boys on roll up to aged 13.
Male pupils will remain under the changes but the senior boys programme will end in July 2022.
In a statement, headteacher Jo Sharrock said: “Shrewsbury High School has been educating girls in the heart of Shrewsbury for over 135 years. From next September, we will truly become one school, with our Prep relocating from its current site to unite with our historic senior school on one super site, at Town Walls.
"We will be going back to our roots, concentrating our full energies on what we know and do best – the all-through education of girls. From next September all pupils, from Reception to Year 13, will be together - cementing our place in the heart of our lovely town.
“Since becoming head here, my team and I have given much thought to how the school can best continue to thrive and our 135th anniversary year feels like the right time to take this decision. Shrewsbury High is now consistently achieving high standards across all areas of school life: examination results, pastoral care and co-curricular activities.
"We have a strong ethos, clear vision and, financially, we are in a good position. We have exciting and ambitious plans for development and innovation. Plans that cannot be realised with part of our school on the site we currently lease at Roman Road.
“During lockdown, when we provided our online Guided Home Learning programme, we had the opportunity to operate much more cohesively as one school. It was a wonderful experience, with benefits for every year. We now have the opportunity to truly become one school, to design a bespoke Junior School and to invest in our existing facilities on one super site which can be enjoyed by all our pupils.
"There will also be great value in having the youngest through to the oldest pupils on one site, learning and working together. We are extremely enthusiastic about the benefits this move will bring for all our pupils. These are exciting times.”
The school has written to parents about the changes, and virtual meetings about the changes will be held next week.
Girls' School Day Trust chief executive Cheryl Giovannoni added: “I’m so excited by these plans to bring all the pupils together on one site to create the only cohesive, all-through, all-girls, educational offering in the heart of Shrewsbury."