Fajdek represented Poland at the 2008 World Junior Championships in Bydgoszcz, finishing just off the podium in 4th despite throwing a new Polish junior record of 75.31 metres with the 6 kg under-20 implement. In 2009, his first year as a senior, Fajdek placed 8th at the European U23 Championships in Kaunas, Lithuania with a throw of 68.70 metres. Fajdek placed 3rd at the Polish Championships that year with a mark of 70.86, behind former Olympic and World Champion Szymon Ziółkowski and a returning Wojciech Kondratowicz. In 2010 he grabbed another national bronze, this time with a throw of 73.85 metres; later that year, he improved his personal best to 76.07, good enough for 35th in the world.
Fajdek continued to improve in 2011, finishing second at the European Team Championships in Stockholm with a new personal best of 76.98 metres. He improved further to 78.13 at Madrid, beating among others the reigning Olympic Champion, Primož Kozmus of Slovenia. He was an overwhelming winner at the European U23 Championships in Ostrava, Czech Republic, beating second placer Javier Cienfuegos by five and a half metres to record yet another personal best of 78.54. He also dominated his speciality at the World University Games in Shenzhen, winning the gold with 78.14, more than four metres ahead of silver medallist Marcel Lomnický; a week later at the World Championships in Daegu, however, he only managed 75.20 and finished eleventh.
Fajdek first broke 80 metres at the Ostrava Golden Spike meeting in May 2012, finishing second to Hungary's World silver medallist Krisztián Pars. In his next competition at Montreuil he threw yet another personal best of 81.39, this time beating Pars.
|2008||World Junior Championships||Bydgoszcz, Poland||4th||Hammer throw (6 kg)||75.31 m|
|2009||European U23 Championships||Kaunas, Lithuania||8th||Hammer throw||68.70 m|
|2011||European U23 Championships||Ostrava, Czech Republic||1st||Hammer throw||78.54 m|
|Universiade||Shenzhen, China||1st||Hammer throw||78.14 m|
|World Championships||Daegu, South Korea||11th||Hammer throw||75.20 m|
|2012||Olympic Games||London, United Kingdom||–||Hammer throw||NM|
|2013||Universiade||Kazan, Russia||1st||Hammer throw||79.99 m|
|World Championships||Moscow, Russia||1st||Hammer throw||81.97 m|
|Jeux de la Francophonie||Nice, France||1st||Hammer throw||78.28 m|
|2014||European Championships||Zürich, Switzerland||2nd||Hammer throw||82.05 m|
|2015||Universiade||Gwangju, South Korea||1st||Hammer throw||80.05 m|
|World Championships||Beijing, China||1st||Hammer throw||80.88 m|
|2016||European Championships||Amsterdam, Netherlands||1st||Hammer throw||80.93 m|
|2016||Olympic Games||Rio de Janeiro, Brazil||17th (q)||Hammer throw||72.00 m|
|2017||World Championships||London, United Kingdom||1st||Hammer throw||79.86 m|
|Universiade||Taipei, Taiwan||1st||Hammer throw||79.16 m|
|2018||European Championships||Berlin, Germany||2nd||Hammer throw||78.69 m|
|2019||World Championships||Doha, Qatar||1st||Hammer throw||80.50 m|
|2021||European Athletics Team Championships||Chorzów, Poland||1st||Hammer throw||82.98 m|
- "Hammer Throw (6kg) – M Final". IAAF. 12 July 2008. Retrieved 18 July 2011.
- "European Athletics Result Service". European Athletic Association/Tilastopaja. 19 July 2009. Retrieved 18 July 2011.
- "Trzeci dzień Mistrzostw Polski w Bydgoszczy" (in Polish). Polski Związek Lekkiej Atletyki. 3 August 2009. Retrieved 18 July 2011.
- "86. Mistrzostwa Polski Seniorów BIELSKO-BIAŁA, 8–10 lipca 2010" (in Polish). Magazyn Lekkoatletyczny. 10 July 2010. Retrieved 18 July 2011.[permanent dead link]
- "2010 Toplists ht m". IAAF. Retrieved 18 July 2011.
- "European Athletics Result Service". EAA/Tilastopaja. Retrieved 18 July 2011.
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- "RESULTS" (PDF). 17 August 2011. Archived from the original (PDF) on 7 October 2011. Retrieved 8 June 2012.
- "Hammer Throw – M Final". IAAF. 27 August 2011. Archived from the original on 2 March 2014. Retrieved 8 June 2012.
- "Polak drugi na świecie w rzucie młotem" (in Polish). rp.pl. 24 May 2012. Retrieved 8 June 2012.
- "OSTRAVA GOLDEN SPIKE : Results". Zlatá Tretra Meeting. 24 May 2012. Retrieved 8 June 2012.
- "Paweł Fajdek z rekordem! Rewelacyjny wynik Polaka w rzucie młotem!" (in Polish). sport.pl. 5 June 2012. Retrieved 8 June 2012.
- "Czesław Cybulski Anita Włodarczyk" (in Polish). MistrzowieSportu.pl. 25 August 2009. Retrieved 18 July 2011.
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