The title Earl of Haddington was created in 1627 for Sir Thomas Hamilton in the Peerage of Scotland, Earl of Melrose. Hamilton wanted to replace "Melrose", the title having been created in 1619, with "Haddington". Therefore, King Charles I granted the Haddington Earldom, and the Melrose title was relinquished. Though the earldom of Haddington was created in 1627, it is, for the purposes of precedence, treated as if it were created in 1619- the date of the creation of the earldom of Melrose.

The fifth Earl of Haddington, Charles, was married to a woman who held the Earldom of Rothes. The couple decided that it would be best to keep the titles separate; therefore, it was decided that the earldom of Rothes would go to their eldest son, while the earldom of Haddington would go to their younger son, from whom all future Earls of Haddington have descended.

The only subsidiary title held by the Earl is Lord Binning and Byres (created 1613), which is the courtesy title for the eldest son of the Earl.

The family seat is Mellerstain House in the Scottish Borders.

Earls of Haddington (1627)

• Thomas Hamilton, 1st Earl of Haddington (1563-1637)
• Thomas Hamilton, 2nd Earl of Haddington (1600-1640)
• Thomas Hamilton, 3rd Earl of Haddington (1628-1645)
• John Hamilton, 4th Earl of Haddington (1626-1669)
• Charles Hamilton, 5th Earl of Haddington (c. 1650-1685)
• Thomas Hamilton, 6th Earl of Haddington (c. 1680-1735)
• Thomas Hamilton, 7th Earl of Haddington (1721-1794)
• Charles Hamilton, 8th Earl of Haddington (1753-1828)
• Thomas Hamilton, 9th Earl of Haddington (1780-1858)
• George Baillie-Hamilton, 10th Earl of Haddington (1802-1870)
• George Baillie-Hamilton, 11th Earl of Haddington (1827-1917)
• George Baillie-Hamilton, 12th Earl of Haddington (1894-1986)
• John George Baillie-Hamilton, 13th Earl of Haddington (b. 1941)