In 1921, Marotti won the first Italian Championship in Viareggio. In 1922, he took 16th (i.e. last place) in London (José Raúl Capablanca won), but had a fine win against Eugene Znosko-Borovsky. In 1923, he was Sub-Champion in Naples (2nd ITA-ch). Marotti lost a match for the title to Rosselli (+2 –6 =5). In 1923, he took 11th in Triest (Paul Johner won). In 1927, he took 3rd in Naples (Rosselli won). In 1928, he tied for 4-5th in Perugia. In 1928, he played for Italy in the 2nd Chess Olympiad at The Hague (+3 –7 =2). In 1929, he took 11th in Venice (Rudolf Pitschak won). In 1930, he took 3rd in Florence (Rosselli won).