Smirnow contested his first World Cup race in December 1982, the 15 km run in Davos |. In March 1983 he won the Junior World Championships in Kuopio , Finland , he became vice world champion over ten kilometers and won the gold medal with the Soviet 3x5 kilometer relay. He celebrated his first victory in the World Cup in 1986 in Kavgolovo. He won a total of 29 World Cup races, becoming the overall World Cup winner in 1991 and 1994. In October 1988 he suffered a broken arm, but he was able to make up for the training deficit and on February 18, 1989 in Lahti, he won the world championship gold medal in the 30 km classic competition. At the World Ski Championships he won five gold, three silver and three bronze medals. He was most successful in 1995 in Thunder Bay , when he became three-time world champion.
Smirnow took part in four Olympic Winter Games from 1988 to 1998 . In 1994 he became the first Olympic champion for the independent Kazakhstan and in the same year he was the first Kazakh to receive the Holmenkollen Medal . He befriended his greatest rivals, Norwegians Vegard Ulvang and Bjørn Dæhlie , and appeared on some of Dæhlie's television shows. Smirnov headed the Almaty city bid committee for the 2014 Winter Olympics , but the bid was not considered for the second round in June 2006.