His father, also Ninian Niven, was a gardener at Keir House near Stirling, and travelled to the Cape of Good Hope twice collecting plants for George Hibbert and the Empress Josephine of France.

[1] Niven was invited to take up the position of head gardener of the grounds of the official residence of the chief secretary for Ireland in the Phoenix Park, Dublin in 1827.

Here he concentrated his efforts on expanding the plant collection, as well as restoring and improving the layout of the neglected gardens.

He also designed the Iveagh Gardens for the great exhibition of 1865, and Hilton Park, Clones, County Monaghan in 1870.

During the Great Famine, he published a pamphlet, The potato epidemic and its probable consequences, in the form of an open letter to Augustus FitzGerald, 3rd Duke of Leinster.

He mistakenly attributed the cause of the potato disease to atmospheric conditions, unlike David Moore, who correctly deduced the cause of the blight.