[1][2] Between 1952 and 1964 he took part in 363 ski races, finishing within the podium in 263 and winning 134 of them; during this period he won four world titles and nine Olympic medals.

In 12 starts over three consecutive Winter Games he never finished worse than fifth place, and between 1955 and 1960, he won 86 out of 161 competitions.

"[7] For his cross-country skiing successes, Jernberg was awarded the Holmenkollen medal in 1960 (shared with Helmut Recknagel, Sverre Stensheim and Tormod Knutsen).

He was also awarded the Svenska Dagbladet Gold Medal in 1956 (shared with pentathlete Lars Hall).

In 1965, the International Olympic Committee awarded Jernberg the Mohammed Taher Trophy for his contributions to Nordic skiing.