The 3.5 million Performing Arts Centre has been created in the Grade A-listed assembly hall at Stewart's Melville College, off Queensferry Road.
The 580-seat venue will be available for groups around Edinburgh to use and has been praised as a valuable addition to the Capital by the Scottish Chamber Orchestra.
The orchestra will perform at its official opening on Sunday, September 23.
Erskine Stewart's Melville Schools have spent seven years planning and raising funds for the venture, which boasts an innovative design and top-quality acoustics. More than 1.4m has been gathered through fund- raising, with the rest of the money coming out of the schools' own accounts.
Although the 1850s building was carefully preserved during the renovation, the floor was lowered by 10ft to improve the views from the gallery. The move also created steep seating, which will allow those in the back row to feel as though they are right on top of the performance.
David Gray, principal of the Erskine Stewart's Melville Schools, which encompasses The Mary Erskine School, Stewart's Melville College and The Mary Erskine and Stewart's Melville Junior School, said: "This was very much designed for the wider community. It should be a huge asset for Edinburgh and people like the Scottish Chamber Orchestra. The sight lines are excellent and the acoustics are first-class.
"There are side partitions that can reduce the capacity to just 300 for more intimate performances. It will give us a great focus for the performing arts, which, along with sports, have traditionally always been strong here."
As well as music concerts, it will be used as a recording studio, and a venue for theatre productions and conferences.
Mr Gray said: "It is a lot of money, but it is going to be used by a wide range of people and the quality has to be first-class.
"We were concerned that, whatever the cost, it should have a stamp of quality."
A Scottish Chamber Orchestra spokeswoman said: "We are looking forward to performing at the venue for the first time.
"The new centre looks set to become a welcome addition to Edinburgh's performing arts facilities."
As well as the school's own performances, pupils have appeared in West End hits such as Chitty Chitty Bang Bang and Joseph and his Technicolour Dream Coat, while more than 900 youngsters regularly take music classes.
Bryan Lewis, vice-principal of the Erskine Stewart's Melville Schools and headmaster of The Mary Erskine and Stewart's Melville Junior School, said: "We have always enjoyed a very high standard of music and drama at Stewart's Melville and Mary Erskine, but until now there has been no material evidence of its value on the Stewart's Melville site."
Chris Duffy, manager of the Performing Arts Centre, added: "We have first-class lighting and sound equipment, which will support every type of performance. The architects, Simpson and Brown, worked closely with theatre and acoustic consultants to ensure that this venue would be a centre of excellence for the arts - not only for the schools, but for the whole of Edinburgh."