Models operating in the fashion hub will be required to provide doctor's certificate to state their overall physical health and prove their body mass index (BMI) sits within a healthy range.
The index, a measure of weight in relation to height and age, will be compared to the World Health Organization's standards of underweight to decide whether a model is certified.
Marisol Touraine, French minister of social affairs and health, explained the new rules on Friday in a statement, saying that they were aimed at avoiding the promotion of inaccessible beauty ideals and preventing youth anorexia.
The previous version of the law, backed and adopted by French parliamentarians in late 2015, suggested a minimum BMI for models and up to six-month imprisonment for employers who violate it. However, it prompted protests from the country's fashion industry.
In addition, another law obliging magazines and advertisers to label digitally altered images will come into force on October 1.
According to the law, images where a model's appearance has been manipulated need to be labeled "photographie retouchee" (retouched photograph).
I do believe that the real reason for this law is because the winds are getting stronger in France and you don't want these girls swirling about the Champs Elysees like pieces of news print and ending up on peoples wind screens.