Maitland was a member of an ancient family of both Berwickshire and East Lothian, the eldest surviving son of John Maitland, 2nd Lord Maitland of Thirlestane (d. 1645), (who had been created Viscount of Lauderdale in 1616, and Earl of Lauderdale etc., in 1624), and of Lady Isabel (1594–1638), daughter of Alexander Seton, 1st Earl of Dunfermline and great-grandson of Sir Richard Maitland of Lethington, the poet.
