The Robertsons claim to be descended from Crinan, Lord of Atholl, from whom sprang the royal house of Duncan I, the King of the Scots. The Robertson clan is more properly called 'Clan Donnachaidh' from their ancestor Duncan, who was a staunch supporter of Robert the Bruce, and who led the Clan at the Battle of Bannockburn.

The general surname of the clan Robertson was taken from Robert Riach (Grizzled Robert) the clan chief, who was known for his intense loyalty to the Stewarts. Riach was responsible for capturing the murderers of King James I, and was rewarded by the crown for this act by having his lands at Struan erected into a Barony.