Son of Italian immigrants Vitorio Lorenzato and Gema Terenzi, he grew up in a meadow in the Colônia Agrícola do Barreiro. In the 1910s, he attended the Silviano Brandão School Group and learned the basics of wall painting from the Italian Américo Grande. In 1919, he sold all his assets and returned to Italy. Until 1924, Lorenzato worked in the reconstruction of the city of Arsiero, destroyed during the clashes of World War I (1914-1918). In 1925, he moved to Vicenza, where he enrolled in the Reale Accademia delle Arti. In 1926, he traveled to Rome and met the painter and caricaturist Cornelius Keesman, with whom he left, in 1928, for the Asian continent, traveling through a great deal of Eastern Europe.
In 1930, he faced problems with his passport and returned to Italy. In 1935, he moved to Montevarchi and married Emma Casprini. During the World War II (1939-1945), the intensification of bombing in Castelnovo destroyed his house, his studio, and the works he had done until then. In 1948 he returned to Rio de Janeiro. Lorenzato worked as a wall painter until 1956, when, while painting the exterior of two apartments, he fell and broke one of his legs. It was from the second half of the 1950s that he devoted himself entirely to painting.
In 1964, Lorenzato visited Galeria Grupiara, in Belo Horizonte, and presented some of his works to the journalist and art critic Sérgio Maldonado, who introduced him to the critic and journalist Palhano Júnior. In 1967, he held an individual exhibition at the Minas Tênis Clube. Between the second half of the 1960s and the beginning of the 1970s, he participated in collective exhibitions at Galeria Guignard and Galeria Minart. In 1973, he was selected to represent Brazil at the Third Bratislava Triennial in Slovakia. In 1995, the Pampulha Museum of Art held the retrospective show Lorenzato e as Cores do Cotidiano [Lorenzato and the Colors of the Daily Life].
In 2000, the shows 100 Years of Amadeo Lorenzato, at Núcleo de Artes Casa dos Contos, and Amadeo Lorenzato, at Manoel Macedo Galeria de Arte, were held to celebrate the artist's centennial. Recent solo exhibitions include Lorenzato: simples singular, at Minas Tênis Clube (2018), Amadeo Luciano Lorenzato, at David Zwirner, and Amadeo Luciano Lorenzato, at S|2, both in London (2019), and Lorenzato: Landscapes, at Gomide & Co (2022). His works are part of the collections of different museums and public collections, such as Fundação Clóvis Salgado and the Pampulha Museum of Art in Belo Horizonte, the Federal University of Viçosa, Pinacoteca de São Paulo, and MASP – Museu de Arte de São Paulo Assis Chateaubriand.