After 71 years, Moffats School, at Kinlet Hall, Kinlet, will close in July.
Chairman Julian Engleheart said: “We have always been a small school by choice, maintaining the family ethos of our founders.
"However, the current financial climate is putting enormous pressure on small schools and we have decided that it would be unwise to commit to a new year this September.
"However, we will continue to run educational activities in our lovely house and grounds, which provide such a wonderful environment for learning.
“We have a very busy, exciting six weeks of term ahead of us. Over the next few months we hope to give news of our plans for the future.”
Moffats School is a boarding and day school for children aged three to 13.
Moffats was founded in 1934 by children’s writer Natalie Engleheart. The school began in a Hertfordshire house called Moffats, once the home of 16th century naturalist Thomas Moffat.
Natalie was assisted by her sons John and David, who served as joint heads for many years, and whose own children and grandchildren now in turn have roles in the school.
As the Second World War loomed, the school moved to Lifton Park in Devon. In 1946 Moffats moved again, this time to Kinlet Hall.