The St John, later St John-Mildmay Baronetcy, of Farley in the County of Southampton, is a title in the Baronetage of Great Britain. It was created on 9 October 1772 for Paulet St John, Member of Parliament for Winchester and Hampshire. The second Baronet represented Hampshire in the House of Commons. The third Baronet was Member of Parliament for Westbury, Winchester and Hampshire. He married Jane, daughter of Carew Mildmay, and assumed the additional surname of Mildmay. The fourth Baronet sat as Member of Parliament for Winchester. The title became dormant in 1955 on the death of the tenth Baronet. In 1998 Walter John Hugh St John-Mildmay successfully proved his right to the title and became the eleventh Baronet.
Several other members of the family have also gained distinction. Hervey George St John-Mildmay (1817-1882), son of Paulet St John-Mildmay (1791-1845), second son of the third Baronet, was a captain in the Royal Navy. George William St John-Mildmay (1792-1851), third son of the third Baronet, was a captain in the Royal Navy. John Francis St John-Mildmay (1795-1823), fourth son of the third Baronet, was a captain in the Royal Navy. Humphrey St John-Mildmay, sixth son of the third Baronet, was Member of Parliament for Southampton. His son Humphrey St John-Mildmay was Member of Parliament for Herefordshire. Francis Mildmay, son of Henry Bingham Mildmay, another son of Humphrey St John-Mildmay, sixth son of the third Baronet, was elevated to the peerage as Baron Mildmay of Flete in 1922 (see this title for further information on this branch of the family). The Venerable Carew Antony St John-Mildmay (1800-1878), seventh son of the third Baronet, was Archdeacon of Essex. Grace Audrey Laura St John-Mildmay, wife of the opera manager John Christie, was daughter of the tenth baronet.
The family surname is pronounced "Sinjun-Mildmay".