The Ukrainian Orthodox Church has been agreed to be independent of the Russian Orthodox Church in Moscow on Thursday.
"With its actions, Constantinople is crossing a red line and catastrophically undermines the unity of global Orthodoxy", said Alexander Volkov, a spokesman for Russian church leader Patriarch Kirill.
"This is a victory of good over evil, light over darkness", Poroshenko said in televised remarks, adding that Ukraine has been waiting for this "historic event" for more than 330 years.
Ukraine now has three Orthodox communities - those that stay under Moscow's control and two schismatic churches.
As UNIAN reported earlier, the exarchs of the Ecumenical Patriarch, who were in Kyiv in September as part of preparations for granting autocephaly to the Ukrainian Orthodox Church, arrived in Istanbul, where on October 10 they were addressing the Synod.
"Thus, the above-mentioned have been canonically reinstated to their hierarchical or priestly rank, and their faithful have been restored to communion with the Church", it said.
Patriarch Filaret, head of the Ukrainian Orthodox Church of the Kiev Patriarchate, conducts a service at the Volodymysky Cathedral in Kiev, Ukraine, Thursday, Oct. 11, 2018.
"Moscow wants that there would be resistance; we, Ukrainians, don't want resistance", he told a briefing.
The Moscow Patriarchate has already downgraded its ties with Bartholomew I over the affair, which it considers an unjust encroachment on its spiritual territory.
"Of course, people will take to streets and protect their sacred sites", Hilarion, a bishop in charge of diplomacy at the patriarchate, was quoted by Russian agencies as saying at a religious congress in Kazakhstan.
Ukraine and Russian Federation have been at loggerheads since 2014 when Kiev street protests urging Ukrainian integration with Europe prompted the ousting of pro-Moscow president Viktor Yanukovych.
Recognition of a Ukrainian church that is not under Moscow's jurisdiction has been an increasingly fraught issue amid the high tensions over Russia's annexation of Crimea and its support of separatist rebels in eastern Ukraine.