Rabbi Shimon Lavi, also known as Shimon ibn Lavi, was born in Spain in 5246 (1486). As a child he was expelled with his family in the Spanish Expulsion of 1492 and settled in Fez, Morocco, where he grew up and studied Torah and Kabbalah.

In 5309 (1549) he set out to go up to the Land of Israel, but on the way he was kidnapped by bandits and held for ransom. After being redeemed he came to Tripoli, Libya. Seeing the community's low spiritual state, he decided to remain and became its rabbi. He introduced the Sephardic rite there and instituted customs that became part of the tradition of Libyan Jewry. For more than three decades he served as spiritual leader and dayan of Tripoli, where he is credited with founding religious institutions and reviving Torah study; Libyan Jews regard him as their greatest scholar.

His main work, Ketem Paz, is a commentary on the Zohar on Bereishit and Shemot, written in part to refute the claim that the Kabbalists ascribe corporeality to God; it was first printed in Livorno in 5555 (1795). He also arranged a Tikkun Leil Shavuot according to the custom of Tripoli and wrote poetry.

The best known of his poems is the piyut "Bar Yochai", in honor of Rabbi Shimon bar Yochai, in which he left his signature: in every stanza except the first and the last, the words "Bar Yochai" are followed by one of the letters of his name. It is sung all year round at the tomb of Rabbi Shimon, and especially on Lag BaOmer. Yemenite Jews made it part of Kabbalat Shabbat, Moroccan Jews sing it before Kiddush, and the Jews of Tunisia and Libya sing it every Shabbat, festival and family celebration.

He passed away in Tripoli on 15 Av 5345 (10 August 1585), at about one hundred years of age, and was buried there.