Ion Guzun began as an investigator at the Dubasari District Prosecution Office and later at the Riscani District Prosecution Office in Chisinau. He put on a magistrate’s robe in 1993, when he was appointed to the Buiucani District Court in the capital. Ten years later he took off the robe in order to try himself as a laDistrict Prosecution Officewyer. After eight years of activity as a defender, he put on again the magistrate’s robe, at the Bender Court of Appeals, and in two years he was promoted to the Supreme Court of Justice (CSJ).

Ion Guzun was part of the justice panel at CSJ who let free a criminal leader named Ion Druta, alias John the Writer (Vania Pisateli), in 2014. This decision was debated within the disciplinary board of the Higher Council of Magistrates, which issued a warning to the judge.

The judge is married to Maria Guzun, a judge at the Court of Appeal, and their son Denis is serving as a judge at the Chisinau Court since 2016.