Following the end of his playing career, Fornalik began a managing career.[2] He was manager in Górnik Zabrze and Odra Wodzisław. He won the bronze medal (3rd place) with Ruch Chorzów in the 2009–10 Ekstraklasa season. In the 2011–12 season he led Ruch Chorzow to second place, the highest placement since winning the title in 1989.
On 19 September 2017, he became the manager of Piast Gliwice.[7] Under Fornalik's rule, Piast turned into overachievers, consistently competing for spots in the upper half of the table, which resulted in winning the championship at the end of the 2018–19 season, finishing third two years later and two short-lived European campaigns. On 25 October 2022, following a poor start to the 2022–23 campaign, Fornalik left Piast and was replaced by Aleksandar Vuković two days later.[8]
On 29 November 2022, Fornalik was announced as the new head coach of Zagłębie Lubin, agreeing to a contract until the end of the 2023–24 season.[9] He extended his deal for a further year on 26 June 2024.[10]