Has taught at the Hebrew University in a variety of positions since 1978. His M.A. thesis (1978, supervised by J. Blau), "Jewish Settlements in Babylonia during the Talmudic Period" traced Talmudic place names that survived in the geographical literature. His Ph.D. thesis (1983, supervised by M.J. Kister), "On the Prophet Muhammad's Activity in Medina" studied the so-called Constitution of Medina and several other topics relating to Muhammad's Medinan period.

Michael Lecker studies early Islamic texts, with an emphasis on the life of the Prophet Muhammad. It is not clear exactly how Muhammad's classical biography came into being. What is certain is that it is a product of the first Islamic century. While reflecting several rival viewpoints, the many solid facts it includes help us establish the broad lines of Muhammad's life and time. Lecker also founded the Jerusalem Prosopography Project.