He had previously held managerial positions as several clubs, including Ajax where he reached the final of the UEFA Europa League in 2017, Borussia Dortmund, Bayer Leverkusen and Lyon, before being appointed as manager of PSV in June 2023, winning the Dutch Eredivisie title in 2024.

After a loan season with then amateurs AGOVV in 1984, he returned to professional football with RKC Waalwijk (from 1985 to 1988), then moving to France with Toulon (1988 to 1991), and playing six successive seasons with Dutch giants Feyenoord (1991 to 1996), Japanese club JEF United Ichihara (1996–97), German club Hansa Rostock[2] (1997–98), NAC Breda[3] (1998–99).

Bosz made his debut for the Netherlands in a December 1991 Euro qualification match against Greece and earned eight caps, scoring no goals.

After his retirement, Bosz started a career in management, first becoming head coach of amateurs AGOVV, a position he held from January 2000 to 2002.

While at the club, he was responsible for completing the signings of (amongst others) Giovanni van Bronckhorst, Roy Makaay, Tim de Cler, Kevin Hofland and Denny Landzaat.

[9] In the summer of 2010, Bosz started his second spell as manager of Heracles Almelo, replacing Verbeek who had moved to AZ Alkmaar in the meantime.

Also, Bosz was nominated for the Rinus Michels Award (for manager of the year), but lost to Phillip Cocu, who had led PSV Eindhoven to the Eredivisie title.

[12][circular reference] In May 2016, Ajax announced that Bosz was the new head coach of the club from July 2016, after signing a three-year contract.

[11] In his first competitive match as head coach, Bosz's side earned a 1–1 draw against PAOK in the third qualifying round of the Champions League on 27 July 2016.

[13] Bosz was unable to lead Ajax to the group stage of the Champions League, after losing 5–2 on aggregate to Russian side Rostov.

[21] Bosz was sacked in March 2021, after the team dropped to sixth place with seven points to direct UEFA Champions League qualification.

[22] On 29 May 2021, Bosz was appointed as head coach of French side Lyon and signed a two-year contract, replacing Rudi Garcia.