Gene Robinson was elected by a two-to-one majority of both the clergy and the laity belonging to the House of Deputies, the lower house of the Episcopal Church’s legislative body, officials said.
The term Episcopal is used in the US to refer to the Anglican church, which has 70 million followers across the world.
The historic move to bring the gay priest into bishops' ranks occurred Sunday at the church's 74th general convention in Minneapolis, Minnesota.
The House of Bishops still has to ratify the vote on Monday. If confirmed, Robinson will take up his post in the diocese of New Hampshire.
The question of whether the first openly gay man in a long-term homosexual relationship would be approved to the post was the overriding issue for Anglican delegates from the US and the world.
Anglican Communion fears
The debate over Robinson's confirmation and recent arguments about same-sex unions have stoked fears of a split in Anglican ranks, with conservative activists vocally opposing both measures.
A group of 24 conservative US bishops, backed by religious
leaders in Africa and other parts of the developing world, have threatened a permanent break with the Anglican Communion if Robinson is confirmed and the church blesses same-sex unions.
"We are the new society God has called into being," cautioned Nigerian Archbishop Josiah Idowu-Fearon from Kaduna province. "It is one people reconciled, of every colour and culture, the one and only family of God. Our church family takes the Episcopal Church very seriously."
In Britain, a leading gay clergyman's move earlier this month to withdraw his decision to accept the post of Bishop of Reading had been seen as a victory for the conservative wing of the Church of England.
The Vatican last week urged Roman Catholics around the world to oppose legalisation of gay marriage.