Weishaupt was born and raised in Ingolstadt, where he studied law and attained the rank of Professor of Canon Law in 1772. Though educated by Jesuits and for a time a member of their order, he broke with them and became increasingly liberal in his religious and political views, favoring deism and republicanism. His interests were widespread, including an early fascination with aeronautics.
With the help of, and occasional fiction with, Bron von Knigge, Weishaupt in 1776 formed the Order of Perfectibilists, which later became known as the Illuminati. Although the Order was founded to provide an opportunity for the free exchange of ideas, Weishaupt's background as a Jesuit seems to have influenced the actual characer of the society, which was determined by an elaborate network of spies and counter-spies.
A year after the society was banned by Bavaria's government in 1784, Weishaupt lost his position at the University of Ingolstadt and fled Bavaria. He received the assistance of Duke Ernest of Gotha, and during the next quarter century lived in Gotha writing a series of works on Illuminism, including A Complete History of the Persecutions of the Illuminati in Bavaria (1785), A Picture of Illuminism (1786), An Apology for the Illuminati (1786), and An Improved System of Illuminism (1787). He died there in 1811.