Once Britain's first woman rabbi, Jackie Tabick is now the first female convenor of the Reform movement's Beit Din, following the retirement of Rabbi Rodney Mariner.
She will take up the part-time post in April, while continuing her congregational role as rabbi of North-West Surrey Reform Synagogue.
Rabbi Tabick will oversee the authority at a time of increased applications for conversion.
More than 70 potential converts are due to come before the Beit Din in the first half of the year. In the whole of 2011, 106 Reform converts were approved.
"I feel privileged to lead this part of the movement's work in such an important and growing area," she said.
"With an estimated half of all Jews now marrying non-Jews, it is vital that we reach out to mixed-faith couples and a significant part of my work will be spent offering them support, regardless of whether the non-Jewish partner intends to convert."
Her new position will further increase the representation of women in the leadership of Reform. Rabbi Laura Janner-Klausner began her new role as movement rabbi at the start of the year; Jenny Pizer is its chairman and Rabbi Deborah Kahn-Harris was recently inducted as principal of Leo Baeck College.
Reform chief executive Ben Rich said Rabbi Tabick "will bring a wealth of experience and a great deal of sensitivity to the role, even if it does leave me as the last man standing".
Ann Antrich, joint chairman of North-West Surrey, said the appointment was "a matter of great pride for us.
"Not only does she lead our community in the educational and spiritual side of Jewish life. She also plays an important role in pastoral care, experience which I'm sure will be important for her work with the Beit Din."