Igor Popa’s career started in 1999 as an interim assistant and later as an investigator, at the Riscani District prosecution office in Chisinau, and later he took the same job at the Center District prosecution office in the capital.

In 2002 Mr. Popa was assigned at the Prosecutor-General's Office, where he served as a deputy chief and later as the chief of the department for investigation of outstanding cases. During this mandate he was publicly accused of forging dossiers on demand and abuse of office. In the report released by the Parliament’s ad-hoc commission for investigation of the April 2009 riots, it was Igor Popa who had urged the judges to stage the trials of dozens of detained young protesters right inside the police stations - in plain violation of the existing procedures.

In 2010, Igor Popa resigned from the office of chief of the department for outstanding cases but continued acting as a full staff prosecutor in that department. A year later he was transferred to the department for special missions. In February 2012 Mr. Popa won a contest for the post of chief prosecutor of the Riscani District in the capital.

In December 2015 Igor Popa was appointed the interim chief prosecutor of the capital and in three months he became the chief prosecutor. In 2017 he competed for the post of prosecutor-general of Moldova but lost to Eduard Harunjen, who made Mr. Popa one of his deputies. In 2019 as the public learned of the illegal tapping of opposition figures and journalists, Mr. Harunjen resigned from office and the prosecution service. Mr. Popa tried his chances again but this time lost to Alexandr Stoianoglo.

In early 2020, Igor Popa returned to the Chisinau Prosecution Office as its deputy chief and headed in parallel the Ciocana District prosecution office.