John St John, 11th Baron St John of Bletso

John St John, 11th Baron St John of Bletso (died 24 June 1757) was an English peer.

The son of Andrew St John and his wife Jane Blois, daughter of William Blois of Cockfield Hall, Suffolk, he was a nephew of Paulet St John, 8th Baron St John of Bletso and succeeded his brother Rowland St John, 10th Baron St John of Bletso to the family title in 1722.

Lord St John married Elizabeth Crowley (the daughter of Ambrose Crowley) at Greenwich on 6 March 1725. Their children included:

• John St John, 12th Baron St John of Bletso
• St Andrew St John, Dean of Worcester
• Henry St John, a Royal Navy captain
• Anne, married in 1761 Cotton Trefusis, mother of Robert Trefusis, 17th Baron Clinton
• Barbara, who in 1764 became the second wife of George Coventry, 6th Earl of Coventry.
• Jane, who married Humphrey Hall.

British comedian and actor Alexander Armstrong is a direct descendant of Lord St John.