At the age of 3 an uncle of his, who was from Milan, gave him hospitality in Rome, but he ended up with living there eighteen years. After his uncle's death he returned to Milan, where he graduated in law and began working as a lawyer. His life suddenly changed in the thirties when, during a performance at the Opera House to which the student had worked hard, he met Andrea Rizzoli, who was looking for new and skilled people for a humorous newspaper that he published, called "Il Bertoldo". Among other journalists there was Vittorio Metz. This experience and friendship gave birth to his varied activities as a journalist, screenwriter, director, actor, writer and humorist. Since then on he began working as a journalist for several newspapers, and for radio programs, as well as for the theater for actors such Gino Bramieri, Walter Chiari, Carlo Dapporto, Wanda Osiris, Vittorio De Sica, Alberto Sordi and Ugo Tognazzi. In 1937 he created for the Italian EIAR (Public Hearing Italian radio) a radio program titled "Radioenciclopedia A2". In 1939 he wrote "Cinquemila lire per un sorriso", directed by Corrado Mantoni, and when Vittorio Metz decided to move to Rome, Marcello followed him there. The first movie scripted by Marchesi and Metz was, "Imputato, alzatevi", starring Erminio Macario, in 1939. He continued writing plays even during the World War II. Marcello was also a singer and was the songwriter of many singers, as well as being the first to launch new actors such as Sandra Mondaini, Gino Bramieri, Sophia Loren, Walter Chiari, Gianni Morandi, Paolo Villaggio, Cochi and Renato. He was also a screenwriter and, together with Vittorio Metz, he wrote many movies in which Totò had the leading role, until the late fifties. He directed seven movies, among them "Era lui… sì, sì!", starring Walter Chiari and "Lo sai che i papaveri". From 1932 until he died he also wrote several books, including poems. He is considered the first Italian copyrighter because, since the birth of the Italian television, he created more than 4,000 "caroselli" and a lot of well-known advertising slogans. In 1952 he returned to Milan and during the fifties, when the Italian television was born, he was the screenwriter of many Italian television shows. Among them there was Walter Chiari in "La via del successo", "L'amico del giaguaro", with Corrado Mantoni, Gino Bramieri, Raffaele Pisu and Marisa Del Frate, "Quelli della domenica" – 1968 -, where Paolo Villaggio became famous acting in the role of "Fracchia" and "Doctor Krantz", as well as several editions of "Canzonissima". In 1963 he appeared as a screenwriter and television presenter together with Lina Volonghi and Sandra Mondaini in "Il signore di mezza età". In 1976, at the age of 6,4 he married his second wife Enrica Sisti, more than 30 years younger than him, and became the father of Stefano Massimo. On July 19, 1978 while swimming with his son Massimo in the sea near Oristano, he was unfortunately hit by a very strong wave. Marcello was thrown on a rock, hit his head against it and died instantly without anyone could do anything.