Though Olegário Mariano's contributions to Brazilian culture were of enormous importance in the fields of poetry and literature; he was also the lyricist of some important songs. 42 of his songs were recorded by famous artists and he left other songs published. He also wrote the libretto of the operetta Mariúsa (music by Joubert de Carvalho). His most regular partner was Joubert de Carvalho; the duo has written 24 songs, 19 of which were published and recorded, and many of them are still popular until today. "Cai, Cai, Balão" and "Tutu Marambá" (recorded by Gastão Formenti, who also recorded "Hula," "De Papo Pro Ar," and "Zíngara") are still part of Brazilian childhood. His poem "Seu Zé Raimundo" had music by Jaime Ovalle and was recorded by Patrício Teixeira (1926). Two years later, Hekel Tavares put music to several others poems of his (like "Sapo Cururu," recorded by Francisco Alves in 1929). His lyrics also had music by Ary Barroso ("Tu Qué Tomá Meu Home," recorded by Araci Cortes in 1929), Gastão Lamounier ("Arrependimento," recorded by Gastão Formenti in 1929, "Reminiscência" and "Suave Recordação"). Hekel Tavares and the pioneer of the Brazilian theatre Procópio Ferreira declaimed some of his poems in several records. Other famous artists that recorded the Joubert/Mariano duo were Francisco Alves ("Dor De Recordar," 1929) and Carmen Miranda ("Absolutamente," "Se Você Quer," and "Bom-dia, Meu Amor," between 1931 and 1933).
At age eight he came to Rio de Janeiro with his parents. Before he was 13, he was already writing poetry. At 12, he published his first book, Angelus. He would also go on to write Visões De Moço (1911), Sonetos (1912), Evangelho da Sombra e do Silêncio (1913), Canto da Minha Terra (1913), Água Corrente (1917), Últimas Cigarras (1920), Castelos Na Areia (1922), and Cidade Maravilhosa (1923). In 1926, he was elected for the Academia Brasileira de Letras (Brazilian Literature Academy); after that, he published Bataclan (1927), Destino (1931), Poemas de Amor e de Saudade (1932), Teatro (1932), Coletânea de Tradutores (1932), Poesias Escolhidas (1932), O Amor Na Poesia Brasileira (1933), Vida, Caixa de Brinquedos (1933), O Enamorado da Vida (1937), Da Cdeira No. 21 (1938), Abolição Da Escravatura E Os Homens Do Norte (1939), Em Louvor Da Língua Portuguesa (1940), A Vida Que Já Vivi (1945), Quando Vem Baixando O Crepúsculo (1945), Cantigas De Encurtar Caminho (1949), Tangará Conta Histórias (1953), having had the body of his works published under the title of Toda Uma Vida De Poesia (1958). He was also congressman in 1934, secretary of the Brazilian embassy at Bolivia, plenipotentiary minister at Portugal, and ambassador of Brazil at Portugal, among many other duties and distinctions.