[2] Ericsson started competing internationally in 1951 at the European Allround Championships where he did not qualify for the final distance.

The next year, Ericsson became the 1955 European Allround Champion, ahead of Shilkov (who took silver) and Dmitry Sakunenko (who won bronze).

Two weeks later, Ericsson became World Allround Champion in Moscow, beating Goncharenko (silver) and Shilkov (bronze) on their "home ground".

[2][3][4] Ericsson then participated in the 1956 Winter Olympics and he won silver on the 5000 m, behind world record holder Boris Shilkov, but ahead of bronze medallist Oleg Goncharenko.

But Ericsson managed to beat the time set by Johannesen by one second, setting a new Olympic record and becoming Olympic Champion on the 10000 m.[2] Later in February that year, Ericsson finished only 6th at the 1956 World Allround Championships and he won bronze at the European Allround Championships.