On 5 June 2009 he took over Lech Poznań, where he won the league in his first season with the team. After crashing out of Champions League qualifications in the third round, Zieliński led the team to the top of their Europa Leaguegroup table after the first two games. However, Lech was underperforming in the league, with the team temporarily stranded at the very bottom of the table. On 2 November 2010, he was dismissed.
After a two-year hiatus, Zieliński returned to Polish football as a manager on 10 November 2021, taking charge of Cracovia for a second time in his career.[2] Following a 2–2 home draw to last-placed ŁKS Łódź on 5 April 2024, he was dismissed.[3]