Kaczmarek had been part of the Lechia Gdańsk youth team, before being promoted to the first teamat the beginning of the 1990 season. Kaczmarek made his Lechia debut in a 2-0 win over Hutnik Warsaw in 1991. Throughout his time at Lechia, the team were not very successful and found themselves at the lower ends of the I Liga. Kaczmarek's most successful season with Lechia was in 1993-94, in which he played 32 games and scored 9 goals. At the age of 21, Kaczmarek joined Ekstraklasa team Pogoń Szczecin. After facing relegation with Pogoń to the I Liga, they were soon back in the top flight by 1997. In the January transfer window of 1998, Kaczmarek joined fellow Ekstraklasa team GKS Bełchatów. Unfortunately for Kaczmarek, Bełchatów were relegated at the end of the season. After two more seasons with Bełchatów in the second division, Kaczmarek had short spells with Unia Tczew, in which he was plagued by injury, before joining Stomil Olsztyn. After his time at Stomil, Kaczmarek rejoined Lechia Gdańsk for a season.
Managerial career
Kaczmarek's first managerial position was with Lechia Gdańsk in 2004. Under his guidance, Lechia achieved promotion from the fourth tier to the second tier of Polish football. After achieving safety for Lechia in the I Liga, Kaczmarek joined Pogoń Szczecin. After managing the team for the first half of the season, Kaczmarek was told he would not be manager for the second half. After his short spell with Pogoń, Kaczmarek took charge of Olimpia Grudziadz in 2008. His 4 seasons with Olimpia were succeccful, his command saw Olimpia winning the III liga in 2009, and the II Liga in 2011. After successful spell at Olimpia, Kaczmarek joined recently relegated Wisła Płock in 2012. In his first season Wisła won the third tier, ensuring promotion back to the I Liga. After three more seasons at Wisła, Kaczmarek saw his side finish runners-up in the I Liga, and saw one of his teams being promoted to the Ekstraklasa for the first time. His first season in the Ekstraklasa saw Wisła finish comfortably in 10th. In 2018 Kaczmarek joined recently relegated Bruk-Bet Termalica Nieciecza in the I Liga. Ahead of the 2019-20 season, Kaczmarek was appointed manager of Widzew Łódź.
