Washington's 106-year-old National Cathedral is often used for presidential funerals and inaugural prayer services.
Cathedral officials say the church will be among the first Episcopal congregations to implement a new rite of marriage for gay, lesbian, bisexual and transgender members.
It may take six months to a year before the first gay marriages are performed at the cathedral due to its busy schedule.
The Rev. Gary Hall, the cathedral's dean, said performing same-sex marriages is an opportunity to break down barriers and build a more inclusive community "that reflects the diversity of God's world." Hall, who has been an ordained minister for more than 35 years, said he has long been an advocate for gay marriage and began performing same-sex blessings in 1990 when he served at All Saints Church in Pasadena, Calif.
The Human Rights Campaign, the nation's largest gay rights group, applauded the cathedral's change as a milestone.
"Today, the church sent a simple but powerful message to LGBT Episcopalians - you are loved just the way you are, and for that we embrace you," said the Rev. MacArthur Flournoy, the deputy director of HRC's religion and faith program.
The conservative National Organization for Marriage, which opposes same-sex marriage, said the cathedral's change was "disappointing but not surprising," given the direction of the Episcopal Church.
Same-sex marriage is now legal in nine states and the District of Columbia. Legislators in Illinois and Rhode Island are set to take up bills to possibly join them, and the Supreme Court is scheduled to hear cases on gay marriage in March.
The Associated Press contributed to this report.