Lavie was born in Kfar Saba and attended the religious Bar-Ilan High School in Netanya, and was also a member of the Bnei Akiva youth movement. After graduation, she served in the IDF as an educator. Upon completing her service, she continued in a similar role in her work with the Society for the Protection of Nature in Israel. She married attorney Zuriel Lavie in 1987, after which the couple served as emissaries of Bnei Akiva in Durban, South Africa. They have four children and currently reside in Netanya.
Lavie studied at Bar-Ilan University, where she received a BA in 1988, an MA in 1997 and a PhD in 2002. From 2000 until her election to Knesset in 2013, she served as a senior lecturer at the university's School of Communications. Her doctoral dissertation, "Israel Radio and Gender" (2002), dealt with the issue of gender newsreels and current affairs programs on public radio. She also spent a year as a research fellow at Brandeis University, analyzing media and gender and the cultural role of women in Judaism.
Until she began her work in Knesset, Lavie headed the Center for Media and Religion at Bar-Ilan University. She also taught courses including Gender and Mass Communication, Radio as a Social Instrument, Media and Religion and Advertising Products as Cultural Space.
Lavie's public activity began in 1988, when she became an advisor to Shaul Yahalom, then-political secretary of the National Religious Party. She was Executive Director of the Public Council for Youth Exchange between 1990 and 1996, and founder and chair of Matan (Beit Midrash) Netanya and A Voice (Religious Women's Forum), an organization which served as a founder of the Committee of Management and sexual harassment. Lavie is also a member of the Kolech forum for religious women and a board member of the "Izun" center for treatment and rehabilitation of youth in drug-related or spiritual crisis following backpacking trips overseas.
Lavie's social initiatives concern issues in conversion. She is one of the founders of the Public Committee for Conversion and one of the initiators of the petition filed in the High Court against the marriage official who refused to register the marriage of a woman converted during her military service.
Prior to the 2013 Knesset elections she joined the new Yesh Atid party led by Yair Lapid, and was placed seventh on the party's list. She was elected to the Knesset as the party won 19 seats, and became Chairwoman of the Committee on the Status of Women and Gender Equality. She was also a member of the Finance committee, the National Security and Foreign Affairs Committee., and the House Committee in the 19th Knesset.
She was placed tenth on the party's list for the 2015 elections, and was re-elected as the party won 11 seats. Lavie currently sits on the Committee on the Status of Women and Gender Equality as head of the Subcommittee on Human Trafficking and Prostitution. She also serves on the National Security and Foreign Affairs Committee, the Ethics Committee, and the House Committee. She is head of the Knesset caucus on religion and state, and she is a member of a number of other parliamentary lobbies.
In July 2015 MK Lavie was named "Outstanding Member of Knesset" by the Israel Democracy Institute, for her activities in the 19th parliamentary session.
Lavie published A Jewish Woman's Prayer Book in 2005, a collection of prayers which draw from a variety of Jewish traditions; The English translation won the 2008 National Jewish Book Award from the Jewish Book Council in the United States. She also wrote The Jewish Backpack and is the co-editor of To Be a Jewish Woman.