In 1925 he finished the Riga 2nd Secondary school. In 1929 he started the studies in University of Latvia, the Faculty of Mathematics and Natural Science. In 1934 he graduated from the University of Latvia. In 1933 he was practicing in Krakow, Poland, at Krakow Astronomical Observatory under supervision of Tadeusz Banachiewicz, and continued there until 1936. In 1933 he calculated the orbit of asteroid1933 OP, discovered by Karl Wilhelm Reinmuth, and named it 1284 Latvia; this is the first minor planet to bear a Latvia-related name. After 1951 he worked at the University of Latvia as professor at department of Theoretical Physics. He became an associate professor (docent) in 1956, and professor in 1966. He became a member of the IAU in 1958, and of the Astronomy council of the USSR Academy of Science in 1967.
Karlis Steins has enriched the astronomy with the research in cosmogony, celestial mechanics and problems of precise time. He has over 120 publications. Ph.D. degree was obtained in Pulkovo Observatory in 1963 by defending the thesis on Evolution of comet orbits.