Born in Sortavala in what was then Eastern Finland and is now the Republic of Karelia, Russia, Hiltunen and her mother moved to Helsinki after her father’s death in 1941. There she studied at the Finnish Art Academy where she twice won the prize for sculpture.
In 1944, the year of her first exhibition, she married photographer Otso Pietinen, who by the 1960s managed Scandinavia’s largest photo studio. In 1956, they built a studio house in Helsinki where over the years Hiltunen transitioned from figurative to abstract expression and to direct welded sculpture. In 1967, she bought a medieval tower in the Italian town of Monticchiello which she restored as her Italian home and studio.
Hiltunen is most famous for her famous Sibelius monument in the Sibelius Park, Helsinki, completed in 1967 after she won a 1962 design competition organised by the Sibelius Society following the composer's death. Although her sculpture of some 600 stainless steel pipes is now regarded as an important Finnish landmark, its initial reception was controversial because of the abstract design. Versions of this monument now stand in the grounds of the United Nations headquarters in New York City, in Montreal and outside UNESCO in Paris. There are more public art works by Hiltunen on display internationally than by any other Finnish sculptor in such major cities as Jeddah, Teheran, Montreal, Paris, Berlin, and Rome.
During her career, Hiltunen sculpted at least 32 medal designs including, as well as her medals for the Nordic series, medals commemorating Jean Sibelius, Winston Churchill, Ingmar Bergman, Carl Axel Nordman, HIH Empress of Iran Farah Diba, and the USA Bicentennial. After much debate, Anders Nyborg finally persuaded her to design the first two medals in his series, for Greenland and Iceland, by promising he would take her to Reykjavik to present the Iceland medal to the country’s president. The fine quality of her work on these medals established the pattern for the succeeding series.
Fluent in six languages, Hiltunen met many heads of state, politicians, and celebrities during her long career. In 1982, she was bestowed with the title of Commendatore for her contribution to Italian-Finnish cultural exchange, and in 2001 she was awarded the Finland Prize. She died in Helsinki in 2003.