A native of Podolia, Leiba Nevakhovich moved to St. Petersburg where he, Nota Notkin and Abram Perets were at first housed by Catherine II's priest. A brilliantly educated man knowing several foreign languages, Lev Nevakhovich was an official translator in St. Petersburg. In this capacity he translated into Russian important documents concerning the case of rabbi Shneur Zalman who was under investigation. At the end of his life Nevakhovich, like Perets, adopted Lutheranism.
In 1803 Nevakhovich wrote the book "Lamentation of the Daughter of Judaea" in Russian which he dedicated to Interior Minister Count Kochubey. It was the first Russian-language book on a Jewish subject. Nevakhovich appealed to Russian people to view the Jews as their fellow countrymen and strongly opposed change of religion as a means of emancipation. "Would it be decent of us to reject our law in order to achieve emancipation?" he wrote. A year later Nevakhovich translated his book into Hebrew and dedicated the translation to his friends Perets and Notkin. In honor of the crowning of Alexander I Nevakhovich wrote an ode dedicated to the Emperor.
Nevakhovich contributed to many Russian magazines. He also authored the play "Suliots, or Spartans of the Eighteenth Century" which was staged at the Alexandrinsky Theater. For this play the Emperor granted him a gold snuffbox with diamonds. In 1806 Nevakhovich adopted Christianity. He served at the State Revenues Department of the Ministry of Finance and continued his literary activity. Many of his descendants were well-known people. One of his sons published the humor magazine "Yeralash", while another was the head of the Repertoire Department at the Imperial Theater Board.
A well-known scientist, biologist Ilya Mechnikov, was one of his grandsons.