Born in Saint Petersburg in the Russian SSR, he began training in athletics at the Leningrad sports club. He won his first major international medal at the 1983 Summer Universiade, taking the bronze behind America's Mike Carter and Zlatan Saračević of Yugoslavia. At age twenty-two, he made his global senior debut for the Soviet Union at the 1983 World Championships in Athletics, though he failed to get past the qualifying round. Smirnov made quick improvements in the 1985 season, establishing himself among the world's best shot putters. His throw of for the gold medal at the 1985 European Cup was a championship record – one that would go unbeaten right up until the European Cup became defunct in 2009. He beat Alessandro Andrei and Udo Beyer to win the event. His throw was the second best ever by a Soviet athlete at that point, behind only the mark of set by Sergey Kasnauskas the previous year. His first national title win came at the Soviet Athletics Championships, where he topped the podium with a throw of. He remained in good form at the 1985 IAAF World Cup, taking the silver medal after Ulf Timmermann. Smirnov ranked second globally on performance that year behind Timmerman's world record throw.
Peak and indoor medals
He reached his athletic peak in the 1986 season. He threw a Soviet and Russian record distance of in Tallinn, although again he was beaten by Timmermann. He was victorious at the Soviet Championships for a second time and his winning mark of was the best ever at the meet. He set a meeting record of at the Brothers Znamensky Memorial, which as of 2015 remain unbettered. Internationally he won two medals that year. He was the silver medallist at the 1986 European Athletics Indoor Championships behind Swiss champion Werner Günthör. The Goodwill Games in Moscow brought him the second gold medal of his career, beating national rival Sergey Gavryushin and American John Brenner. Becoming the inaugural champion with a throw of, his mark was never bettered at the games. He comfortably qualified at the 1986 European Athletics Championships, but picked up an injury and was unable to start the final, which was won by Günthör. He placed third in the world on distance that season after East Germany's Beyer and Timmermann. This was Smirnov's last top three outdoor ranking of his career. He won a third straight national title in 1987 and also claimed his first win at the Soviet Indoor Athletics Championships. The indoor circuit was his focus that year and he claimed two bronze medals, first at the 1987 European Athletics Indoor Championships and then at the 1987 IAAF World Indoor Championships, placing behind Timmermann and Günthör at both events. He achieved a lifetime indoor best performance of to win his indoor national title in Penza and, as of 2015, this remains the Russian indoor record. It was six centimetres short of the Soviet record held by Sergey Kasnauskas.
Olympic debut and later career
He was defeated at the national championships by Gavryushin in 1988, but still gained selection for the Soviet Union at the 1988 Summer Olympics. At the 1988 Seoul Olympics he ranked fifth in qualifying but throw a little shorter in the final, resulting in an eighth-place finish for his only Olympic appearance. His best throws that year were in Vilnius and in Moscow. He did not compete internationally in 1989 and his season's best of was his worst since 1983. He returned in 1990 and ranked sixth in the world through his season's best of and narrowly missed out on a medal at the 1990 European Athletics Championships, taking fourth place after Norway's Georg Andersen. Smirnov won his last two Soviet national titles in 1990 and 1991 at the national indoor meet. He ranked second on distance indoors globally in both those years. He was ninth at the 1991 IAAF World Indoor Championships and also won a silver medal at the 1991 European Cup. Smirnov acquired Russian citizenship in 1992 and began competing intentionally for the newly independent nation. His only major appearance for Russia was the 1993 IAAF World Indoor Championships, where he placed seventh. He was the inaugural winner of the shot put at the Russian Indoor Athletics Championships that year. He ranked first in the world indoor rankings in 1992 through his mark of .
