St John’s College in Southsea near Portsmouth is to close after 114 years due to falling pupil numbers the BBC reports.
Pupils will be able to take exams this year as planned, but the school for four to 18-year-olds will not reopen in September.
Pupil numbers at the co-educational day and boarding school have fallen from 630 in 2010 to 256 this year.
The school, once attended by BBC newsreader George Alagiah, was founded by the De La Salle brothers in 1908 and it retains their Christian values.
Head of college Mary Maguire said: “It is heartbreaking. We all love this school, and this is the very last thing we would have wanted to happen.”
She said the school was working to find alternative places for pupils at nearby schools and opportunities for staff.
Chair of governors Zenna Hopson blamed the pandemic and years of “chronic under-investment”.
She explained staff had hoped the school would be bought and investment provided for the site to be redeveloped and allowed to continue. But she said the deal fell through.
“We are desperately sorry, and we are doing all we can to support our pupils, their families and our staff,” she added.
The planned closure is the latest in a series of post-Covid closures of independent schools.