Patriarch Kirill put his name to the document after worshipping with campaigners from the For Life and Orthodox Volunteers groups.
His Grace (below) thanked them for their efforts and blessed them.
The Russian Orthodox Church has always opposed abortion, however some see this as a hardening of its stance in that it calls for a blanket ban on all abortion - including births where there could be potentially fatal complications for the woman or in cases of rape.
The Church has denied this, saying: "The fact of the signing of the Patriarch of the public initiative to ban abortion is not something new in the Church's position.
"It is well known as not only the Orthodox, but representatives of all traditional religions of Russia related to abortion.
"This position is tough and unambiguous."
The petition reads:
"We, the citizens of the Russian Federation, are in favour of the termination of the existing practice of abortion in our country which is the legal killing of children before birth and require making changes in the legal system to recognize that a conceived child has a status of human being, whose life, health and well-being should be protected by law."
It has also said that the first step to criminalising abortion would be to remove from coverage in the country's mandatory health insurance scheme, where they argue it is presented as a "social norm".
The Supreme Mufti of Russia Talgat Tadzhuddin and the Children's Rights Commissioner of Russia Anna Kuznetsova have also backed the petition.
According to the Daily Express Gennadiy Onischenko, the Chief Sanitary Inspector of Russia, said: "There can absolutely clear and certain medical reasons for abortion... It is when mother's life is in danger, or she suffers from a certain disease.
"A woman in a dead-end situation will take some medicine to lose her pregnancy.
"It will end up with an abortion anyway, and a huge risk to the woman's health."
