A precocious but sickly youth, his promising career was cut short in its infancy when he died of consumption in Locarno, Switzerland, at age 21.
As a result, Mielck's œuvre is small; his most acclaimed compositions are the Symphony in F minor (Op.
He started piano lessons at the age of ten; in 1891 he was sent to Berlin, where he studied under Max Bruch, one of the leading composers of the period.
Mielck faced disappointment in his home country for the lack—with the exception of the Finnish Suite—of nationalistic (political) tendencies; his interest in the culture of his ancestral Germany made him rather a foreigner in the Finnish music scene.
The enthusiasm aroused in the critics—mainly Karl Flodin [fi] in Nya Pressen [fi]—by the premiere of Mielck's symphony, on 20 October 1897, conducted by Robert Kajanus, was a motivation that prompted Jean Sibelius to try his hand at a symphony.