Grzegorz Zajączkowski (born 25 June 1980) is a Polish sprinter who specializes in the 400 metres.
Zajączkowski was part of Poland's 4 × 400 metres relay at the 2003 World Indoor Championships, together with teammates Rafał Wieruszewski, Marcin Marciniszyn and Marek Plawgo. The team originally finished in 4th place,[1] but received bronze medals after the 1st place USA team was later disqualified.[2]