The law gives regional authorities the power to bar unaccompanied under 18s from some public places, "for example, in the street, stadiums, parks, squares, public transport and Internet cafes" between 10:00 p.m. and 6:00 a.m.
The amendments to the law on children's rights will also ban minors from visiting night clubs, bars, restaurants and other places which sell alcohol, as well as sex shops, although the age of consent in Russia is 16. The law also gives local authorities the right to draw up a list of other places that could harm children's "physical, spiritual and moral development."
Police officials have said the move could also help tackle the problem of neglected and homeless children, as police will have to either return them to their homes or place them in orphanages, and it will force parents to take greater care of their children.
Children's rights groups have criticized the law as an infringement of children's rights and freedom. In Russia, children are considered full-fledged citizens after 14, when they are granted passports.
Some ombudsmen said the law demonstrated the authorities' inability to curb criminal activity, and doubted it would be observed by minors.
The amendments, approved by the upper and lower houses of parliament earlier this month, give regional authorities the right to cut the upper age bracket to 16 years and delay the "curfew" hour "in line with seasonal and climatic conditions."
The amended law also obliges authorities to encourage education, sport and other appropriate pastimes for children and stipulates punishment for parents whose children are not at home after 10:00 p.m.