The winning song combined rap and traditional folk music.
Ukraine was ranked fourth, according to the jury’s vote, but it won by a large margin in the viewers’ vote. British singer Sam Ryder ranked second.
Kalush had been expected to win the annual competition, which is usually watched by nearly 200 million people on television, partly because of Ukraine’s post-war suffering in February.
The band’s leader, Ole Bisik, said last week that he hoped to win a victory to “uplift the morale” of his compatriots. This is the third time that Ukraine has won the Eurovision contest.