The 47-nation Council of Europe has fought for abolition of the death penalty since the organization was founded in 1949. Capital punishment is not allowed in Europe, and no execution has been carried out on the continent since 1997.
Last week, Poland clashed with its EU counterparts over the proposal to hold an anti-death penalty day, demanding that it is linked to a wider debate on abortion and euthanasia, which are both illegal in the deeply Roman Catholic country.
But while the 27 EU countries - all of which are also Council of Europe members - needed unanimity to commemorate the day, the Council of Europe decided by a qualified majority, meaning it didn't need Poland's accord.
Poland did not take part in the vote, while the other 46 countries supported the idea to mark the anti-death penalty day, officials said.
Abolition of the death penalty is one of the cornerstones of the European Convention on Human Rights, an international human rights treaty binding on all Council of Europe members, and a key condition of membership of the organization. Poland eliminated the death penalty in 1997 and says it has no plans to reintroduce it.
About 70 countries worldwide still carry out the death penalty.