Giovanni Antonio Guardi, also known as Gianantonio Guardi (1699 – January 23, 1760) was an Italian painter. Guardi was one of the founders of the Venetian Academy in 1756.

Born at Vienna, he was the son of a minor Baroque painter from Trentino, and the elder brother of the more famous Francesco Guardi.

He may have received his artistic training in Vienna, where he is first recorded in 1719, but had established a workshop in Venice by 1730. Among his first important clients was the connoisseur and collector Johann Matthias von der Schulenburg, for whom Guardi produced copies after the work of other artists, as well as a series of Turkish-inspired interiors as easel pictures for private decoration. Antonio Guardi trained his younger brothers Nicolò and Francesco in his workshop, the latter working closely with him as a figure painter before establishing himself as a vedutista in the late 1750s.

A founder member of the Accademia Veneziana in 1756, the elder Guardi produced several works for churches in Venice, notably in the church of the Angelo Raffaele, as well as decorative cycles for palaces and villas in the city and the surrounding terraferma.

Francesco Casanova was among his pupils.

He died in Venice in 1760.