Mattia Bortoloni (31 March 1696 – 1750) was an Italian painter of the Rococo period, mainly active in the area of Bergamo and Venice.
He was born in the town of San Bellino in the Polesine region of the Province of Rovigo. He trained with Antonio Balestra of Verona. Bortoloni painted the 104-panel fresco cycle at Villa Cornaro, a Palladian villa in Piombino Dese near Padua. He also painted a ceiling in the Ca' Rezzonico. Other examples of Bortoloni's work are displayed at various monuments in the Veneto and Lombardy, including the parish churches at Castelguglielmo and Fratta Polesine, and in the ceilings at the Church of San Nicolò da Tolentino (presbytery, c. 1730) and the palazzo Ca' Vendramin Calergi. Along with Giuseppe Galli Bibiena (of the Galli Bibiena family of artists) and Felice Biella, in 1746–48, Bortoloni helped complete ceiling frescoes in the Vicoforte Sanctuary.
In Venice, he painted Glory of St Cajetan for the ceiling of the choir of the Theatine church of San Nicola Tolentini. He painted a Madonna and Saints for the Hospital of SS. Pietro e Paolo in Venice.
In Bergamo, he worked alongside the Milanese stucco-artist, Riva Palazzi, to decorate the ceiling of the choir, presbytery with figures and decoration. In Brescia, he painted a medallion for the Gallery in the house of Signori Barbisoni. In Ferrara, he painted a Glory of St Thomas Aquinas for the Cathedral and a canvas of Saints Cosma e Damiano for the Oratory of the Speziali.