John Mylne (1611 – 24 December 1667), sometimes known as "John Mylne junior", or "the Younger", was a Scottish master mason and architect, who served as Master Mason to the Crown of Scotland. Born in Perth, he was the son of John Mylne, master mason, and Isobel Wilson. Practising as a stonemason, he also took on the role of architect, designing as well as building his projects. He was one of the last masters of Scottish Renaissance architecture, before new styles were imported by his successors. Alongside his professional career he also served as a soldier and politician. He married three times but had no surviving children.
Mylne learned his trade from his father, assisting him with projects including the sundial at Holyrood Palace. In 1633 Mylne was made a burgess of the royal burgh of Edinburgh, and was admitted to the Edinburgh lodge of masons, both on account of his father's position. He was first appointed to the town council in 1636, and in the same year was appointed master mason to the Crown, succeeding his father.