[4] He won two medals in the 4 × 400 metres relay at the European Athletics Championships.

He attended the Jerzy Kukuczka Academy of Physical Education in Katowice.

Pietrzak competed in the 4 × 400 m relay event at the 2012 Summer Olympics in London.

At the 2013 Indoor European Championships in Gothenburg, his team lost the relay bronze medal due to disqualification; it was judged that one of his teammates had pushed British athlete Richard Buck.

[9] He and his teammates qualified to the 4 × 400 metres relay final at the 2016 Summer Olympics in Rio de Janeiro, Brazil, finishing in 7th place.