Lonkila won a gold medal in the 4×10 km relay at the 1952 Olympics and finished third in the individual 18 km race, 11 seconds behind his teammate Tapio Mäkelä. Earlier his 4×10 km relay team placed second at the 1950 FIS Nordic World Ski Championships, where he finished fifth over 18 km. He won the 18 km event at the 1951 Holmenkollen ski festival. Lonkila was a farmer by occupation.