French MPs have passed a law that makes it illegal to pay for sex and imposes fines of up to €3750 ($NZ6274) for those buying sexual acts.
It has taken more than two years to pass the controversial legislation because of differences between the two houses of parliament over the issue.
About 60 sex workers and supporters demonstrated outside parliament in Paris, and carried banners and placards - one read: "Don't liberate me, I'll take care of myself", the AFP news agency reported.
Members of the STRASS sex workers' union said it would affect the livelihoods of prostitutes, estimated to number between 30,000 and 40,000.
But supporters of the law have said it will help fight trafficking networks, and make it easier for foreign prostitutes to get a temporary residence permit in France, if they agreed to find jobs outside prostitution.
Sex work was decriminalised in New Zealand in 2003.
Socialist MP Maud Olivier, who sponsored the legislation, told the Associated Press news agency the "most important aspect of this law is to accompany prostitutes, give them identity papers because we know that 85 percent of prostitutes here are victims of trafficking".
The law was passed in the final vote on the bill in the lower house of parliament by 64 to 12, with 11 abstentions, France's Le Monde newspaper reported.
It superseded a law from 2003 that penalised sex workers for soliciting.
Those found guilty of paying for sex would have to pay a first time fine of €1500 ($NZ2509), which would more than double for a repeat offence, and they would have to attend classes to learn about the conditions faced by prostitutes.
Sweden was the first country to criminalise those who pay for sex rather than the prostitutes, and Swedish authorities said the number of women on the streets in Stockholm had fallen since the legislation was introduced.