Isaac Nieto (1702–1774) (Hebrew: יצחק ניטו) was Haham of the Portuguese congregation Sha'are Hashamayim, Bevis Marks, London, and the son of David Nieto.
He was officially appointed as "ḥakham ha-shalem" in 1733, but gave up the post in 1741 and went abroad.
In 1751 the London congregation requested him to accept the post of ab bet din, his colleagues being Isaac de Valle and Jacob Coronel.
Nieto wrote a letter of resignation on 17 March 1757, and on the following 14 July he was prohibited from exercising the functions of assessor.
Nieto preached on 6 February 1756, the day of fast and penitence ordered by the king, a Sermon Moral, published in Spanish and English in London, 1756.