ST John's-on-the-Hill School, Tutshill has been sold to Dean Close School, Cheltenham.
The headmaster of Dean Close School was "delighted" to announce the acquisition of the school which will apparently secure its future.
Over recent years St John's has suffered financial burdens that have cast an uncertain shadow over its 222 pupils, aged between three months and 13 years old. Governors hope the new arrangement between the schools will broaden the base of Dean Close and provide a stronger financial position for St John's, giving greater security in the future without an adverse effect on the family scale and pastoral focus of the school.
St John's claims to have enjoyed a "close and successful" relationship with Dean Close over recent years, and has seen significant numbers of pupils move over to its senior school in Cheltenham.
Headmaster at St John's, Nick Folland, said: "Dean Close will take on ownership of the school subject to signing contracts. The sale gives us protective financial comfort.
"St John's will roll on pretty much the same as it has done. We have a meeting with parents on Thursday evening who will meet with prospective governors. We see it as a positive occasion.
"The atmosphere around the school has been wonderful these past few days."
Mr Folland said no jobs will be affected by the sale and education will continue as normal.
Headmaster of Dean Close School, Jonathan Lancashire, said: "St John's is a well-regarded preparatory school with many values in common with Dean Close: a charitable foundation, full co-education, a belief in all-round education and the development of character."
Mr Lancashire continued: "Now that the financial burdens that have overshadowed the school have been removed, we are confident that it has a great future, with its proud traditions, excellent teaching, strong support staff and loyal families."
Parents of the School received a letter on Friday telling them of the acquisition.