Born on June 9, 1886 (Meiji 19) in Hongo, Tokyo, as the child of missionary doctor Yamada Kenzo. Raised in a Christian household, he was familiar with hymns from childhood. In 1904 he entered the Tokyo Music School (today Tokyo University of the Arts), graduating from the vocal-music regular course in 1908. In 1910, with the support of Iwasaki Koyata (of the Mitsubishi zaibatsu), he studied at the Royal High School of Music in Berlin (until 1913), under Max Bruch and learned composition in earnest. In 1912 he composed Japan's first true symphonic works — the symphony 'Victory and Peace' and the symphonic poem 'Dark Gate.' After returning home in 1914, he organized Japan's first full-scale orchestra, the 'Tokyo Philharmonic Society,' and was active as a conductor as well. In 1924, with Konoe Hidemaro, he founded the 'Japan Symphony Orchestra Association' (predecessor of the NHK Symphony Orchestra). From around 1918, partnering with the poet Kitahara Hakushu, he unveiled one after another of the monuments of Japanese children's songs — 'Red Dragonfly,' 'Flowers of Karatachi,' 'This Road,' 'Waiting,' 'Stove,' and others. In 1926 he moved to Chigasaki, his lifelong base. During the war he also composed national and military songs, but postwar he became chairman of the Japan Conductors Association in 1950 and received the Order of Culture in 1956. In 1948 he was half-paralyzed by cerebral hemorrhage, but continued to compose. He died in Tokyo on December 29, 1965, aged 79.

A bright, expansive artist with a strong desire for self-expression. As a conductor he had the weighty style of his German training; as a composer he had his own aesthetic of weaving the inflections of the Japanese language into Western music. The group of children's songs born of his deep friendship with Kitahara Hakushu are works of art in which poem and melody fuse beautifully. On the business side he was careless, and in the Japan Symphony Orchestra Association he clashed with Konoe Hidemaro over accounting issues, causing the faction to collapse. At his home salon 'Kosaku-so' in Chigasaki, many artists gathered.

Yamada Kosaku was both a pioneer of Japanese classical music and a master of children's songs. The orchestral culture he built through his conducting activity is passed down today as the NHK Symphony Orchestra. 'Red Dragonfly' and 'Flowers of Karatachi' are sung across generations as primal landscapes of the Japanese heart. On the other hand, criticism and reappraisal of his composition of many wartime national and military songs have been repeated postwar. Chigasaki has the Yamada Kosaku Memorial Hall, holding his belongings, scores, and autograph manuscripts. As of 2025, with the 60th anniversary of his death approaching, reappraisal continues.