A law enters into force at the moment of its publication in the parliament's official newspaper.
On December 20, the Ukrainian parliament passed a bill requiring the UOC-MP to add the word "Russian" to its name in order to reflect its ties to the country. Ukrainian President Petro Poroshenko signed the bill into law two days later.
With the law in force, the UOC-MP will now have four months to change its name, but the church has said it plans to challenge the legislation in the Constitutional Court.
The Ukrainian authorities and Poroshenko have regularly interfered in church's affairs despite their pledge to not to do so.
The Moscow Patriarchate described the situation as the "legalization of schism," stressing that it would have catastrophic consequences and affect millions of Christians in Ukraine and other countries.