Balderis played in the Soviet Hockey League for Dinamo Riga (1969–1977, 1980–1985) and CSKA Moscow (1977–80), having been transferred to the latter as a precondition for being accepted in the Soviet national team. He was the leading scorer in the 1977 and 1984 seasons, winning the Player of the Year award in 1977. He was the best player of the Latvian SSR in the 1970s and 1980s and the most prolific scorer from the republic, tallying 333 goals in Soviet league play.
Balderis played for the Soviet national team at multiple tournaments, winning the silver medal at the 1980 Winter Olympics and gold medals at the World Championships in 1978, 1979 and 1983. Overall, Balderis played in five World Championships (1976–1979, 1983), 1976 Canada Cup and 1980 Winter Olympics. He was named Best Forward in the 1977 World Championships. Balderis was not selected for the USSR's 1984 Olympic team and played in only one major international tournament after he left CSKA Moscow to go back to play for Dinamo Riga in 1980.
In 1985, Balderis retired and became a coach in Japan. He returned in 1989, when Soviet players were allowed to play in the NHL. Balderis was drafted by the Minnesota North Stars, playing 26 games and scoring 3 goals with 6 assists. He became the oldest player drafted by an NHL team (36) and the oldest player to score his first goal (37). He retired again after one season in Minnesota, but came out of retirement for the second time when Latvia regained its independence. Balderis played several games for the newly recreated Latvian national team (in 1992), serving as its captain and scoring 2 goals. He later coached the team and served as its general manager. As of 2017, he serves as a board member of the Latvian Ice Hockey Federation.[3]
