Małysz began his senior-level ski jumping career on 4 January 1995, finishing seventeenth at the third event of the Four Hills Tournament in Innsbruck. In his first two World Cup seasons he achieved moderate success, winning in Oslo on 17 March 1996 and twice in Japan in January 1997, in Sapporo and Hakuba.
The 2000–01 season marked Małysz's arrival as the sport's dominant force. He won the Four Hills Tournament and ended Martin Schmitt's run of success that had stretched back to 1998–99. He reeled off five consecutive individual victories — in Innsbruck, Bischofshofen, both ski flying events in Harrachov, and Park City — and won a gold medal on the individual normal hill plus silver on the individual large hill at the 2001 World Championships. He wrapped up his first World Cup title with three further wins in Falun, Trondheim, and Oslo, also claiming his first Nordic Tournament title.
He defended his overall title in 2001–02, maintaining the lead in the World Cup standings throughout the season despite a burst of five wins by Sven Hannawald in December 2001 and January 2002. At the 2002 Winter Olympics in Park City, Małysz won silver on the individual large hill and bronze on the individual normal hill. In 2002–03, despite struggling for wins in the early part of the season, he took both individual gold medals — normal hill and large hill — at the 2003 World Championships in Predazzo. Three consecutive wins in Oslo and Lahti secured a second Nordic Tournament title. He closed the season by equalling the then-world record of 225 metres in Planica, narrowly holding off Hannawald's late challenge for the overall title.
Following his three consecutive World Cup titles, Małysz could not maintain the same form. He finished twelfth overall in 2003–04 without a win, and fourth in 2004–05 with four victories. The 2005–06 season saw him place ninth overall, with a single win in Oslo.
A significant resurgence came in 2006–07. Małysz opened with a surprise victory in Oberstdorf in January 2007, followed by a double in Titisee-Neustadt. At the 2007 World Championships he won the individual normal hill gold medal. A hat-trick of wins at Lahti, Kuopio, and Oslo gave him a third and final Nordic Tournament title. He then swept all three Planica competitions at the season finale, overtaking Anders Jacobsen in the overall standings to claim a fourth World Cup title, matching Nykänen's record from the 1980s.
Between 2008 and 2011, Małysz collected seventeen additional podiums but did not challenge for the overall title. At the 2010 Winter Olympics in Vancouver, he won silver medals in both the individual normal hill and large hill. His career ended fittingly at home: a victory in Zakopane on 21 January 2011, an individual bronze on the normal hill at the 2011 World Championships in Oslo on 26 February, and third place at the Planica season finale on 20 March. He announced his retirement six days later.
After retiring from ski jumping, Małysz turned to rally driving and competed in the Dakar Rally, one of motorsport's most demanding endurance events. He entered in 2012, 2013, and 2014, finishing 37th, 15th, and 13th respectively — a steady progression that demonstrated genuine competitiveness in his second sporting career.
From 2018 to 2022 Małysz served as director-coordinator of ski jumping and Nordic combined at the Polish Ski Federation. On 25 June 2022 he was elected CEO of the Polish Ski Federation.
Małysz is the only five-time winner of the ski jumping event at the Holmenkollen Ski Festival, having triumphed in 1996, 2001, 2003, 2006, and 2007. He received the Holmenkollen Medal in 2001. He was voted Polish sportsman of the year four times: 2001, 2002, 2003, and 2007. For his sporting achievements he received the Order of Polonia Restituta at three ascending grades: Officer's Cross in 2002, Commander's Cross in 2007, and Commander's Cross with Star in 2010.
On 1 April 2007 Małysz opened a Trophy Gallery in Wisła, housed in the building of the Izabella and Adam Małysz Foundation, displaying the Crystal Globe trophies and major medals from his career.
Małysz was born in Wisła, Poland, to Ewa and Jan Małysz, and has an older sister, Iwona. He trained as a tinsmith-roofer at a vocational high school in Ustroń. On 16 June 1997 he married Izabella Polok; they have a daughter, Karolina, born 31 October 1997. He speaks German, and is a Lutheran.