Juhani Helenius (born May 14, 1933 in Hämeenlinna) is a Finnish sprint canoer who competed in the late 1950s. At the 1956 Summer Olympics, he was disqualified in the heats of the K-2 1000 m event. Four years later in Rome, he was eliminated in the semifinals of the K-1 4 x 500 m event.