He began his professional career in 1989–90 with Jokerit of the SM-liiga and played 21 seasons in the National Hockey League (NHL) for the Winnipeg Jets, Anaheim Ducks, San Jose Sharks, and Colorado Avalanche.

It remains the league record for most goals and points by a rookie and earned him the Calder Memorial Trophy as the top first-year player in the NHL.

He was named recipient of the Bill Masterton Memorial Trophy in 2005–06 for perseverance and dedication to the game and was a member of the Ducks' 2007 Stanley Cup championship team.

[7] As a young adult, Selänne attended business school for two years and served a mandatory one-year stint with the Finnish Defence Forces.

Jokerit moved up to the SM-liiga in 1989–90, and while Selänne missed the majority of the season due to a leg injury, he scored 12 points in 11 games played.

[18] The Jets' organizational philosophy at the time was to allow their European draft picks to develop in their native countries, but by 1991, the franchise was working to bring him to Winnipeg.

[7] Unable to maintain a similar pace in 1993–94—indeed, his rookie totals in goals and points would both prove his career-high by more than 20—Selänne's offensive production declined by 30 percent midway through the season.

[27] He was paired with Paul Kariya, whom he met at the 1996 NHL All-Star Game, and the duo were counted on to lead the young franchise to a postseason berth for the first time.

[5] The NHL created the Maurice "Rocket" Richard Trophy in 1998–99 to be presented to the League's leading goal scorer; Selänne became its inaugural winner following a 47-goal season.

[5] As the Sharks fell out of the playoff race, they looked to make changes; the New Jersey Devils sought to acquire Selänne,[35] but he exercised a no-trade clause in his contract and blocked the deal.

[37] Their hope failed to materialize, however, as Selänne endured a disastrous season in which he scored only 16 goals and 32 points—the lowest totals of his career to that date—and was ultimately relegated to Colorado's fourth line, but was also held out of the lineup as a healthy scratch during a playoff game.

[38] He struggled throughout the year with knee problems that ultimately required surgery, his third such procedure, and with the 2004–05 season canceled by a labour dispute, took the time off to recover.

[39] A free agent when the NHL resumed play in 2005–06, Selänne returned to Anaheim by signing a one-year, $1 million contract with the Mighty Ducks.

[40] Selänne completed the season with 40 goals and 90 points, both of which led the Mighty Ducks,[5] and he was named the recipient of the Bill Masterton Memorial Trophy for dedication and perseverance.

[41] After reaching the Western Conference Final in the 2006 playoffs, the newly renamed Anaheim Ducks entered the 2006–07 season with high expectations; the team brought Selänne back with a one-year, $3.75 million contract.

[42] He reached several milestones during the season: Selänne became the 36th player in NHL history, and second Finn after Jari Kurri, to score 500 goals, on November 22, 2006, against Colorado.

[44] As part of a season in which he again led Anaheim in goals (48) and points (94), Selänne played in his tenth All-Star Game in 2007,[5] and scored his first hat-trick in six years (the 19th of his career) on January 12, 2007.

[5] The Ducks defeated the Wild, Vancouver Canucks and Detroit Red Wings to reach the Stanley Cup Finals; it was the first time in Selänne's career that he played in the NHL's championship series.

[48] He remained undecided on a return—and as a free agent, out of the Ducks lineup to begin the 2007–08 season—until he finally chose to return and signed a one-year contract with Anaheim on January 28, 2008.

[49] He made his return on February 5 against the New York Islanders, and the Ducks posted the League's best record from that point to the end of the regular season by winning 20 of 26 games.

[51] He missed several weeks of the season due to a quad muscle injury suffered when he was cut by his own skate following a hit by Denis Grebeshkov of the Edmonton Oilers,[52] but appeared in 65 games and scored 54 points.

[55] Nonetheless, Selänne appeared in every game for the Ducks and became the oldest player in NHL history to play an entire 82-game season while leading the team with 66 points.

[56] Selänne was named to the Western Conference roster for the 2012 NHL All-Star Game, but declined his invitation and asked the League to instead send his teammate Corey Perry.

He wore the captain's "C" in place of Ryan Getzlaf for the game and as it neared conclusion, received standing ovations from the Anaheim crowd each time he took a shift.

[66] He suffered an abdominal muscle injury that prevented him from playing in the third place game, which Finland won 3–2 over Canada; Selänne and his teammates ended the tournament as the bronze medal winners.

[67][68] The Finns finished one position higher at the 1999 World Championship; The tournament's medal round was conducted in a two-game series format followed by a ten-minute sudden victory overtime if the each team wins one game.

[69] Finland and Sweden split their semifinal, but the Finns advanced to the final in the overtime period after Selänne set up Marko Tuomainen's winning goal.

[7] Selänne served as the Finnish captain at the 2002 Winter Olympics and led his nation to an important preliminary round victory over Russia,[71] however he had only three goals and no assists in four games as the Finns finished in sixth place.

[95] Selänne considers Paul Kariya and Joe Sakic to be the best friends he earned in the NHL,[8] and both attended his final regular-season game against the Avalanche.

[18] He was once named the sexiest man in Finland by fashion magazine Eeva,[8] and is the subject of the 2013 documentary film Selänne, directed by JP Siili, and which chronicles his life.