 At the FIS Nordic World Ski Championships 1926 he placed sixth over 50 km and 13th over 18 km.Niku won nine national titles, in the 10 km (1923–26), 30 km (1921, 1923 and 1925–26) and 60 km events (1925).He also won the 50 km race at the Lahti Ski Games in 1923–25.