Robert II was delivered by Caesarean operation under tragic circumstances by the roadside between Paisley and Renfrew, 2 March 1316, his young mother dying a few hours later. It is said that he picked up an infection during his delivery which affected his general health, and particularly his eyes, for his whole life.

He was declared heir presumptive to the throne, in default of male issue of his maternal grandfather, Robert I, by a Parliament held at Scone, 3 December 1318. He succeeded his father as 7th High Steward, 9 April 1326, and was guardian of the realm from 1338 to 1341 and again from 1346 till 1357, during the reign of his half-uncle, David II. He had to wait until David's death on 22 February 1371, before he inherited the throne; he was crowned at Scone by the hand of William de Landallis, Bishop of St. Andrews, on 26 March following.

Robert II was twice married and had 6 sons and 8 daughters by his two wives and at least 8 illegitimate children by various mistresses, as detailed on his Genealogical Notes page.