John de Mohun, 1st Baron Mohun (died 1330), Lord of Dunster was an English noble. He fought in the wars in Flanders and Scotland. He was a signatory of the Baron's Letter to Pope Boniface VIII in 1301.

John was the eldest son of John de Mohun and Eleanor filias Reynold. He served in Flanders in 1297 and in Scotland. He was a signatory of the Baron's Letter to Pope Boniface VIII in 1301.

He died in 1330 and was succeeded by his grandson John, his eldest son John predeceased him in 1322.

He married firstly Ada de Tiptoft, they had the following issue:

• John de Mohun, Master of Dunster (died 1322).
• William de Mohun
• Thomas de Mohun
• Reginald de Mohun
• Lawrence de Mohun
• Robert de Mohun
• Payn de Mohun
• Joan de Mohun, married John Luttrell, had issue.

He married secondly Sybilla.

•  This article incorporates text from a publication now in the public domain: "Mohun, John de (1270?-1330)". Dictionary of National Biography. London: Smith, Elder & Co. 1885–1900.