In 1989 Jacek Gdański won the silver medal in the World Junior Chess Championship.

In Polish Team Chess Championships Jacek Gdański won eight medals: nine gold (1996, 2000, 2001, 2002, 2003, 2004, 2007, 2008, 2010), seven silver (1990, 1992, 1993, 1997, 2009, 2011, 2012) and bronze (1995).

He won or shared first place in the international chess tournaments: in "Cracovia" (Kraków) (1993, 1994), in Helsinki and Rio de Janeiro (1999).

In 2001 Jacek Gdański qualified for the FIDE World Chess Championship by knockout system in Moscow, where he lost in the first round to Vadim Zvjaginsev.

[5] Jacek Gdański played for Poland in Chess Olympiads:[6] Jacek Gdański played for Poland and Poland Goldies (2013) in European Team Chess Championship:[7] Jacek Gdański successfully combined playing chess at a high level with completing studies at the University of Gdańsk and the National School of Public Administration.