Mattia Bortoloni (* 31. May 1696 in Canda or in San Bellino near Rovigo; 9. June 1750 in Milan) was an Italian painter.
Bortoloni was a pupil of Antonio Balestra in Verona. He worked mainly in the Venice area and in Bergamo. He is known for his frescoes in churches and private houses as well as for his altarpieces.
In 1950 Nicola Ivanov discovered that Bortoloni was the painter of the frescoes in the Villa Cornaro in Piombino Dese near Padua, which had been commissioned in 1716. Other works are in the churches of Castelguglielmo and Fratta Polesine, in the church of San Nicolò da Tolentino in Venice (frescoes, around 1730), in San Vittore in Milan (frescoes), in San Bartolomeo in Bergamo (frescoes), in Turin (consolata, frescoes), in the Santuario della Madonna di Vico near Mondovì (frescoes), in the Palazzo Ca' Rezzonico in Venice (ceiling paintings) and the Palazzo Ca' Vendramin Calergi in Venice. He was also involved in the ceiling frescoes of the Basilica of Vicoforte from 1746 to 1748 (with Giuseppe Galli Bibiena and Felice Biella).
In San Zanipolo in Venice, his painting is Madonna with the martyrs John and Paul, in the Cathedral of Ferrara the preaching miracle of Saint Peter and in S. Trinitate in Rovigo the alms miracle of Saint Thomas of Villanova.