Hanhijoki was born in Rautalampi and represented the club Vesannon Urheilijat. In her early career she competed in the 4 x 100 metres relay at the 1983 World Championships, and in the 100 metres at the 1986 European Championships without reaching the final. She competed at 60 metres and 200 metres at the 1988 European Indoor Championships and the 1989 World Indoor Championships without reaching the final.