When officially opened in September 1947, the New South Wales Government Railways claimed it was the “largest roundhouse in the southern hemisphere”.

Construction started during the later years of WWII when it was realised that the existing locomotive sheds in the triangle north of the station were too antiquated and small. The Junee roundhouse, or loco, as it was called, was the last steam depot built in NSW and as such was the pinnacle of steam depot development in the state. Steam soon gave way to diesel power and Junee loco was accordingly modified and steam facilities such as the coal stage and de-ashing pits removed.