"Son of the Abbot" a reference to the clan's descent from the Pict secular abbots of St. Fillan's near Loch Earn.  When the Pict Celtic church was dismantled, the MacNabs continue to hold their property as the Barony of Glen Dochart.  The MacNabs, similar to the Glen Orchy MacGregors, lost many of their lands after opposing Robert the Bruce, following the murder of their relative, Red Comyn.  However, some of these lands were restored under David II in AD1336.

In 1594, they were listed as one of he broken clans of the Highlands.  Their neighbours were the MacNeishes, a MacGregor sept.  Iain MacNab died fighting for Charles II at Worcester in 1651.  The MacNabs were dispossessed of their lands by the Campbells but they were returned at the Stuart Restoration in 1660.

John MacNab gained fame for his exploits with Montrose,  and his daring escape from capture.  Archibald MacNab fled to Ontario, Canada, to escape his debts in 1823, founding the settlements of MacNab and Arnprior by the Ottawa River.   Sir Allan MacNab became Prime Minister of Canada.