Sir William St Quintin, 4th Baronet (c. 1700 – 9 May 1770), of Harpham and Scampston in Yorkshire, was an English landowner and member of parliament.

He was the eldest son of Hugh St Quintin (b. 1671). He was educated at Newcome's School in Hackney.^[1] He succeeded to the family baronetcy and the Scampston estate near Malton on 30 June 1723 on the death of his uncle, Sir William St Quintin, 3rd Baronet, who had never married.

St Quintin entered Parliament in 1722 as a member for Thirsk, and remained its MP for five years. In 1729–30 he served as High Sheriff of Yorkshire.

He married Rebecca, daughter of Sir John Thompson, Lord Mayor of London, and their children included:

• William St Quintin (1729–1795) who succeeded to the baronetcy
• Mary (d. 1772), who married Vice-Admiral George Darby of Newtown
• Katherine, who married Christopher Griffith, MP, of Padworth
• John Chitty (1730–1746)
• Hugh St Quintin (1731–1736)
• Rebecca St Quintin (d. 1758)