Although best at the longest distances (the 5,000 m and the 10,000 m), Geir Karlstad became Junior World Allround Champion in 1982 and, as a senior, won bronze in both the World and European Allround Championships in 1989.

Among the dominating speed skaters in the 1980s, Karlstad competed at the 1984 and 1988 Winter Olympics, winning no medals.

At the 1992 Winter Olympics in Albertville, he won the gold medal on the 5,000 m and the bronze on the 10,000 m while skating for Lillestrøm SK.

A severe back injury forced him to end his career before the 1994 Winter Olympics of Lillehammer held in his homeland.

He had originally intended to end his career at those Winter Olympics.