NHS Lothian said the £150 million facility at Little France on the outskirts of the city will now not be open until spring 2018 at the earliest.
The replacement hospital was originally supposed to be open by the winter of 2012, only to be held up by a protracted land swap deal.
The opening was delayed again last year after Dunne Group and JB Brickwork, two of the companies working on construction of the hospital, entered administration and provisional liquidation respectively resulting in a temporary pause to their work streams.
The health board said it was putting back the opening date to ensure the “safe and effective” opening of the hospital, which will serve youngsters right across the east of Scotland.
Jacquie Campbell, chief officer for acute services at NHS Lothian, told Forth News: “This is a huge project and it’s vital that we the building is fully operational before it opens to ensure we provide the best possible care to all our patients.
“Staff are being kept up to date with any developments on moving dates.”
Construction work on the hospital started in early 2015. The project is the first acute hospital facility to be procured under the Scottish Government’s Non Profit Distributing (NPD) model.