Families from Fernhill School, on the outskirts of Glasgow, have pledged hundreds of thousands of pounds to tide the school over in the short term and put it on a firmer financial footing for the future.
The eleventh-hour move comes after a meeting between parents and the board on Tuesday evening at which it was announced that Fernhill had been running at a loss and the board had opened discussions with administrators.
Following the meeting, a group of parents began securing pledges to raise money to keep the school afloat and now say they have secured a "significant six-figure sum" that will allow it to operate for up to five years.
The group intends to establish a new board of governors with the expertise to run the school as a viable business.
Fernhill, one of the country's leading Catholic private schools, is based in Rutherglen, South Lanarkshire, and has some 230 pupils and about 40 staff.
A statement from the board said: "We are delighted to be in the position to announce the secured future of Fernhill. A plan has been put in place which will not only save the school from administration, but will also provide a platform for investment in the school's future.
"This has been possible by the swift response of parents who have secured pledges for a six-figure sum to avert the prospect of administration and as a means of refinancing the business.
"The reaction of the parents, teachers and pupils, when the school's future was threatened was overwhelming and is testament to the strength of our community and the quality of education we offer. We look forward to continuing to offer a fantastic education to our pupils in a close and friendly environment and to welcoming new pupils next year."
Parents involved in the rescue plan said it would not have been possible without the goodwill of governors Tony and Kathleen Boswell, who have invested significant sums of money in recent years and therefore have security over the land and buildings.
The pair have agreed to honour existing financial pledges and to allow the school to operate from the premises rent-free for the next five years to give the rescue plan every chance to succeed. Teachers have also agreed to a pay freeze.
Parents were delighted with the unexpected development, with Denise Smith saying: "My 12-year-old and I are in tears together. We are so grateful. Thanks to all who have made this possible and especially the wonderful, inspirational staff."
Valerie Mcghie added: "Lots of emotional tears being shed right now. Well done to those who have made this possible."
An indication of the difficulties facing Fernhill first surfaced in 2011 when the governors took a decision to freeze the fees for two years - although last year fees were raised above the level of inflation and are now £9300-a-year for a senior day pupil.
In 2013, the school introduced a plan to allow families to spread the cost of fees over 10 years to make them more affordable.
Fernhill began as a primary for girls in 1953 run by the Sisters of Notre Dame and was earmarked for closure in 1971. A committee of parents was formed to save the school and the current establishment opened the following year.
A secondary department was opened in 1973 and plans to make the school fully co-educational were announced in 2013.
The last Scottish private school to close due to financial difficulties was St Margaret's in Edinburgh, which called in receivers in 2010.