Costantino Cedini was an Italian painter and art professor.

He was born in Padua. From 1768 to 1771, he was a member of the "Fraglia dei Pittori di Venezia" (painter's guild). His first work was apparently one of four paintings on the history of Alexander and Darius, commissioned by Ferrigo Venier for his family's palace in Dorsoduro (since demolished). He attended the Accademia di Belle Arti di Venezia, where he studied with Giovanni Battista Piazzetta, Giambattista Tiepolo and, primarily, with Jacopo Guarana.

In 1775, he joined a boycott against the nude art classes, led by Giambattista Mengardi (1738–1796), who objected to the length of time the models were required to pose. All the participants, including Cedini, were expelled. Despite this, he and most of the others were readmitted, apparently because of pressure from the University of Padua, which supported their position. He later became a Professor there, from 1784 to 1797. Among his students were Giuseppe Bernardino Bison, Giovanni De Min and Lattanzio Querena.

He retained his membership in the Accademia after purges conducted by the Archduchy of Austria in 1798. He served as Director in 1802 and was reconfirmed as a Professor in 1804, but Venice became part of the Kingdom of Italy in 1805, and after 1807, he was dismissed, as he lacked the necessary Imperial patronage. He died in Venice in 1811.

Many works are attributed to him. Among those known to be his for a certainty are frescoes in the parish church of Torre di Mosto, the Church of St.Barnabas and the Church of St Cassian. He also painted for the nobility, including decorations for the Palazzo Dolfin Manin and the Palazzo Giustinian. In a departure from his usual work, he did some theater curtains for La Fenice in 1792.