Rémy Sicot, 35, was also convicted by a court in Crétail, southeast of Paris, of using false documents to gain money from detainees, Le Parisien newspaper reported.
The former national police officer pocketed $35,000 from a Chinese woman who was arrested December 2008 for not having proper documents.
In another case later the same year, he illegally took 2,000 euros from a Haitian immigrant, also without proper ID documents.
Sicot, who began his career in 2000, was additionally found guilty of stealing two watches from two other detainees on separate occasions in May 2009 and January 2010.
The court heard the officer’s colleagues were astonished to see him turn up at work one day in a fancy German car, although he had previously had financial problems and was travelling to work on a bicycle.
The officer had declared his innocence, saying that his career, to which he had given his all, was more important than money.
The prosecution said the ex-officer’s testimony lacked credibility.
The judge in the case said the defendant was a public employee of the police force who “knew the law and knew perfectly what he was doing”, Le Parisien reported.
The policeman was arrested after complaints were made by detainees.
In addition, the officer’s wife denounced him to investigators before later denying the allegations.
The policeman testified that his spouse had accused him to avenge “marital infidelities”, Le Parisien said.
“I said the truth the first time and I then perjured myself out of love (for her husband),” the woman told the court.