The sievert (Sv), the SI unit representing the stochastic health risk of ionizing radiation, is named for him.

In later years, he focused his research on the biological effects of repeated exposure to low doses of radiation.

He was a founder of the International X-ray and Radium Protection Committee (IXRPC) in 1928, and served as it first chairman; this later became the ICRP.

He also chaired the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

Sievert had an extensive insect collection and his specimens can be found in the Entomological Museum of Lund University in Sweden.