Rossi was born to Stanislao and Teresa Vianello in a house in Calle degli Orbi, in the San Samuele district. The family was well-off.
In 1907 together with his friend, the sculptor Arturo Martini, he went to Paris, where he was attracted by Gauguin's work (as well as that of Van Gogh and the Fauves). In the footsteps of the Tahitian painter, he then went to Brittany, which constituted a great discovery for him. He returned with some works including the famous painting La fanciulla del fiore. Again with Martini he returned to Paris in 1912, where they exhibited together at the Salon de l'Automne, alongside Amedeo Modigliani. His first artistic period, from 1908 to 1914, is underlined by a series of works created in his stays in Burano (which for him and other Venetian painters became a kind of Brittany) and in Asolo. Breton landscapes, views of Burano and Asolo descriptions reveal his different influences, from the synthesis of Gauguin to a certain liberty in stylizations. But these works made of exciting colors are contrasted with others in which the artist denounces a formal research of rigorous constructive commitment. Among these we remember Maternità, from 1913, L'educanda and Signora in verde, from 1914. Called to arms and sent to the front, he suffered the drama of war to the end; the events of imprisonment and particular family crises irreparably shook his mental balance. The return home and the new contacts with art opened new visions and areas to Rossi, who brought his painting to Cubism, going back to the origins of Cézanne's lucid lesson. From 1918 to 1924 (a period in which his illness sharpened to the point of leading him, in 1925, to the asylum Sant'Artemio di Treviso, from which he only died in 1947), he generated some of his works, as critics later acknowledged, among the greatest artists at the origin of modern Italian art.