The governing board of the Synod of the Lutheran Church of Sweden in Uppsala, Sweden, passed the gay wedding proposal 176-73, the Swedish News Agency TT reported.
The decision came three days after the 30th anniversary of the date homosexuality stopped being classified a disease in Sweden.
"The Synod's decision takes a stance in favor of an inclusive view of people. Regardless of whether one is religious or not, this affects the entire social climate and the view of people's equal value," said Asa Regner, the head of the Swedish Association for Sexuality Education. The association is Sweden's largest gay-rights group.
Individual pastors will still be permitted to refuse to perform marriage ceremonies for same-sex couples.
Representatives of the Catholic and Orthodox churches in Sweden expressed their disapproval of the decision in a joint letter to Swedish Archbishop Anders Wejryd.
Church of England spokesman Steve Jenkins said relations between his church and the Church of Sweden may become strained because of the decision.