Bosacki made his debut for Lech Poznań in April 1995, and has won the Polish Super Cup with both them and Amica Wronki in 2004. From 2004 to 2006, he played for Nuremberg.
On 22 May 2006, Paweł Janas called up Bosacki for the 2006 World Cup as a replacement for Damian Gorawski, after the latter failed medical tests upon being diagnosed with severe asthma. Bosacki scored both goals in Poland's group-stage 2–1 win against Costa Rica on June 20, 2006, which were in fact the only goals scored by the Polish national team during the games. He has been capped 20 times for Poland and scored 2 goals.