The mahogany piece was discovered at a country auction in Perthshire in January.
The cabinet, last seen in the 1950s, will be on display at The Lighthouse gallery in Glasgow from this Friday.
It was bought by John Cowie and Jonathan Conkey, owners of furniture restoration, upholstery and design company The Glasgow Guild.
They spotted the Mackintosh piece for sale in Perth.
“We happened to be viewing a sale in Perthshire when we came across the cabinet, which we initially thought must be of the Glasgow School. We both felt it was something special and after some research we were pleased to find it was designed by the great man himself,” Mr Cowie said.
The pair agreed to loan the cabinet for one year, after which they hope to restore the front tapestry panel using the original watercolour of the cabinet design from 1898, which is in Hunterian Art Gallery at University of Glasgow.
The piece of furniture was commissioned by a Mrs Pickering and was last been seen at auction in the 1950s in Dumfriesshire where the Pickerings moved to.
Bailie Liz Cameron of Glasgow City Council said: “This is a perfect fit to have this beautiful Mackintosh piece of furniture being displayed in Mackintosh’s iconic Lighthouse building.”