San Giovanni in Marignano ( or ) is a comune (municipality) in the Province of Rimini in the Italian region Emilia-Romagna, located about southeast of Bologna and about southeast of Rimini. As of 2021, the municipality counts 9,463 inhabitants.
San Giovanni in Marignano borders the following municipalities: Cattolica, Gradara, Misano Adriatico, Morciano di Romagna, Saludecio, San Clemente, Tavullia. It is one of I Borghi più belli d'Italia ("The most beautiful villages of Italy"). Cattolica Airfield is an abandoned World War II US Air Force airfield in its vicinity.
Under the Kingdom of Italy, on 5 December 1895, Cattolica gained municipal autonomy from San Giovanni.
In 1951, 54% of San Giovanni's population was employed in agriculture, falling to 23% by 1971.