Sweden's archbishop is broadly supportive of the move
The Lutheran Church of Sweden - the country's largest - is to conduct same-sex marriages from next month.
Around 70% of the church's 250-strong synod, or church board, voted to back the move, making it one of few global churches to allow gay marriage.
Sweden's government introduced a new law in May allowing gay couples the same marriage rights as heterosexuals.
Three-quarters of Swedes are members of the Lutheran church, though church attendance is low.
The Lutheran Church says gay couples can now get married by any of its priests from the beginning of November.
Individual priests will not be "forced" to perform same sex ceremonies, though substitutes will have to be found if they refuse.
The church - which split from state control in 2000 - backed the government's decision to legalise gay marriage in May.
But some clergy had questioned whether church ceremonies - and the term matrimony - should be reserved for heterosexual unions. Others opposed the move on the grounds it contravened the scriptures.
In response, the Archbishop of Sweden, Anders Wejryd, told reporters: "For my part, the right decision was taken, but I can empathise with the many who believe this has gone too fast."
GAY MARRIAGE IN EUROPE
Netherlands, legalised in 2000
Sweden's largest gay rights group, the Swedish Federation for Lesbian, Gay, Bisexual and Transgender Rights (RFSL), welcomed the move.
"[We] congratulate the Church of Sweden for its decision. [The church's] homosexual and bisexual members will finally be able to feel a little more welcome within society," the group said in a statement.
Sweden was one of the first countries to give gay couples legal "partnership" rights, in the mid-1990s, and to allow gay couples to adopt children from 2002.
It become the fifth European country, after the Netherlands, Belgium, Spain and Norway, to recognise same-sex marriage.