Jocelyn Morffi learned that her contract at St Peter and St Paul's Catholic School in the US city of Miami was being terminated.
Writing on her Instagram page, Morffi said: "This weekend, I married the love of my life and, unfortunately, I was terminated from my job as a result.
"In their eyes, I'm not the right kind of Catholic for my choice in [sic] partner."
She told the Miami Herald she was called into the principal's office last Wednesday and fired when she refused a request that she resign.
Earlier that day, Morffi had returned to the school after marrying her partner of two years Natasha Hass during a service in the Florida Keys.
In a letter to parents seen by NBC 6, the school said: "Today, a difficult and necessary decision has been made regarding Ms Jocelyn Morffi, our first-grade teacher.
"She is no longer teaching at our school."
The Archdiocese of Miami confirmed that she was fired because she broke the terms of her contract - but it did not specify exactly how Morffi had fallen foul of the rules.
Morffi, who also worked as a basketball coach, claims her seven-year career at the school was brought to an end because of her wedding.
Mary Ross Agosta from the Archdiocese told the Miami Herald: "As a teacher in a Catholic school their responsibility is partly for the spiritual growth of the children.
"One has to understand that in any corporation, institution or organization there are policies and procedures and teachings and traditions that are adhered to.
"If something along the way does not continue to stay within that contract, then we have no other choice."
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