The Earldom of Castle Stewart was created in 1800 for the 9th Baron Castle Stewart who became 1st Viscount Castle Stuart in 1793 and 1st Earl Castle Stewart in 1800. The Earl was related to the Marquess of Londonderry, another Irish peer. Lord Castle Stewart was descended from Lord Ochiltree, an illegitimate scion of the Stewart kings of Scotland.

Barons Castle Stewart (1619)

• Andrew Stewart, 1st Baron Castle Stewart (1560-1629)
• Andrew Stewart, 2nd Baron Castle Stewart (d. 1639)
• Andrew Stewart, 3rd Baron Castle Stewart (d. 1650)
• Josias Stewart, 4th Baron Castle Stewart (d. 1662)
• John Stewart, 5th Baron Castle Stewart (d. 1685) (dormant 1685)
• Robert Stewart, 6th Baron Castle Stewart (d. 1686)
• Andrew Stewart, 7th Baron Castle Stewart (1672-1715)
• Robert Stewart, 8th Baron Castle Stewart (1700-1742)
• Andrew Thomas Stewart, 9th Baron Castle Stewart (1725-1809) (revived 1774; became Earl Castle Stewart in 1800)

Earls Castle Stewart (1800)

• Andrew Thomas Stuart, 1st Earl Castle Stewart (1725-1809)
• Robert Stuart, 2nd Earl Castle Stewart (1784-1854)
• Edward Stuart, 3rd Earl Castle Stewart (1807-1857)
• Charles Knox Stuart, 4th Earl Castle Stewart (1810-1874)
• Henry James Stuart-Richardson, 5th Earl Castle Stewart (1837-1914)
• Andrew John Stuart, 6th Earl Castle Stewart (1841-1921)
• Arthur Stuart, 7th Earl Castle Stewart (1889-1961)
• Arthur Patrick Avondale Stuart, 8th Earl Castle Stewart (b. 1928)