The Constitutional Council, which had previously warned that banning the veil may be unconstitutional, said it approved the version of the bill, which has been passed by both Houses of Parliament, after a final review.
It judged however that the ban, due to enter force early next year, would be unenforceable in public places of worship, where it may violate religious freedoms.
"The ban on covering the face in public places cannot constrain the practice of religious freedom in places of worship that are open to the public," the council said in its judgement.Apart from this, the council "judged that the law conforms to the constitution," it wrote.
The text makes no mention of Islam, but President Nicolas Sarkozy's government promoted the law as a means to protect women from being forced to wear Muslim full-face veils such as the burqa or the niqab.
Prime Minister Francois Fillon immediately hailed the judgement as "an important decision to affirm the values of the Republic with respect for freedom of conscience and religion," in a statement.
The ban prohibits anyone from covering their face in public, defined broadly to include not just government buildings and public transport, but all streets, markets and thoroughfares, private businesses and entertainment venues.
Opponents say it breaches French and European human rights legislation.
Once in force, the law provides for a six-month period to explain to women already wearing a face veil that they face arrest and a fine if they continue to do so in any public space.
"The government is preparing measures to inform people, necessary for the law to be properly applied, particularly for the attention of people who harm the founding principles of our democracy by extreme behaviour," Fillon said.
A woman who chooses to defy the ban will receive a fine of 150 euros (US $195) or a course of citizenship lessons. A man who forces a woman to go veiled will be fined 30,000 euros and serve a jail term of up to one year.
