Sammut, who has been the leader of her congregation since 2011, takes over leadership of the International Union of Superiors General (UISG) from Franciscan Sr. Mary Lou Wirtz, the first American to hold the post.
Members of the organization's leadership elected Sammut on Thursday for a three-year term.
The international sisters' group is a membership organization of about 1,800 leaders of the world's congregations of Catholic sisters and nuns. It had been hosting a triennial assembly in Rome this week, focused on the theme of servant leadership, with some 800 members attending.
Pope Francis met with the group in a special private audience last Wednesday, the first time a pope had done so in recent memory.
During their assembly May 3-7, the sisters' group focused on wide questions of authority and obedience in the church, with presentations focused from biblical examples of leadership to "the authority of the suffering."
Addressing that topic Tuesday, Congregation of Jesus Sr. Martha Zechmeister told the women they owe ultimate obedience only to God.
"Religious obedience ultimately can only respond to God's authority," said Zechmeister, a professor of systematic theology at the University of Central America in San Salvador. "In the traditional language, fulfilling the will of God is the only legitimate reason for religious obedience."
The sisters also heard a presentation from Franciscan Sr. Florence Deacon, president of an umbrella group of U.S. sisters called the Leadership Conference of Women Religious (LCWR).
Deacon, who also serves as the superior general of the Sisters of St. Francis of Assisi in St. Francis, Wis., updated the group on a controversial Vatican investigation of LCWR, saying it indicated there were "serious misunderstandings" between Vatican officials and women religious.
Along with Sammut, the sisters' group elected Thursday seven other sisters to serve as members of its board of directors.
Included in the group is one American sister, Sally Hodgdon, who will serve as its vice president.
Hodgdon, who also serves in Rome as the superior general of her international congregation of the Sisters of St. Joseph of Chambery, is a lawyer who once served as an assistant attorney general for the state of Connecticut.
Speaking to NCR during their assembly, Wirtz said a key question facing the organization is how it can work better at assisting the religious of the world.
"We constantly raise among ourselves, 'Is there a way that we can do better as a UISG board for assisting the religious of the world?' " Wirtz said. "We struggle with that question, how can we have better influence?"