Sipilä was Finnish cross country champion in 1923, 1924, 1925 and 1929. At the 1924 Summer Olympics in Paris Sipilä first placed fourth in the 10,000 m race (behind Ville Ritola, Edvin Wide and Eero Berg) and then took part in the 10.65 km cross-country race, which doubled as an individual and team competition. In the extremely hot and demanding conditions, more than half of the participants failed to finish, including Sipilä and two other members of the Finnish team, Berg and Eino Rastas; Finland only barely got a valid team result, even though its stars Paavo Nurmi and Ritola placed a clear first and second. Sipilä was in fourth place in the 6.2 km intermediate standings, ahead of eventual individual bronze medalist Earl Johnson of the United States, but had to drop out shortly after that point.