Kate Kelly, a founder of Ordain Women, said in a blog that she had been informed of her ouster after an all-male panel held a disciplinary trial over her case on Sunday.
The panel convicted her of the charge of apostasy, she said, and has decided to excommunicate her, the most serious punishment that can be levied by a church court.
Kelly, who has campaigned for greater female roles in the church, did not attend the hearing, instead holding a vigil in Salt Lake City in Utah, the home of the Church of Jesus Christ of Latter-day Saints.
"Our determination is that you be excommunicated for conduct contrary to the laws and order of the church," Bishop Mark Harrison, Kelly?s former ecclesiastical leader in Virginia, told her in an email.
The penalties include being banned from wearing temple garments, taking the sacrament, holding a church calling, giving a talk in church, offering a public prayer in church or voting for church officers, it said.
To be allowed back in to the church she must "show true repentance and satisfy" various conditions, it added.
"In order to be considered for readmission you will need to demonstrate over a period of time that you have stopped teachings and actions that undermine the church, its leaders, and the doctrine of the priesthood," it said.
In addition "you must stop trying to gain a following for yourself or your cause and taking actions that could lead others away from the church."
Kelly said: "The decision to force me outside my congregation and community is exceptionally painful.
"Today is a tragic day for my family and me as we process the many ways this will impact us, both in this life and in the eternities. I love the gospel and the courage of its people.
"Don?t leave. Stay, and make things better."
Representatives of the church did not immediately respond to a request for comment on the case.