He was the eldest son and heir of Archibald Kennedy, 1st Marquess of Ailsa but died before his father.
[1] Among his younger siblings were Lady Anne Kennedy (wife of Sir David Baird, 2nd Baronet), Lady Margaret Radclyffe Livingstone Eyre, John Kennedy-Erskine (who married Lady Augusta FitzClarence, an illegitimate daughter of King William IV), and Lady Alicia Jane Kennedy (wife of Jonathan Peel, Secretary of State for War).
[3] He studied at the University of Saint Andrews under the tutorage of James Ferrie, Professor of Civil History.
Together, they had three daughters and nine sons, including:[3][6] Lord Cassilis died on 12 August 1832, before he could succeed to the marquisate.
His eldest son, Archibald, succeeded his grandfather as the 2nd Marquess of Ailsa on 8 September 1846.