Fischer was born in Burglengenfeld, Upper Palatinate. He is a major representative of south German Baroque architects. He studied in Bohemia and combined Bohemian elements with Bavarian Baroque traditions. He often co-operated with the most gifted Bavarian artists of his time, such as Cosmas Damian Asam and Egid Quirin Asam, Johann Joseph Christian, Johann Michael Feuchtmayer, Matthäus Günther, Ignaz Günther, Franz Joseph Spiegler, Johann Baptist Straub, and Johann Baptist Zimmermann.
Fischer designed 32 churches and 23 monasteries in southern Germany. Among these, the best-known are the following.
Several works have been attributed to Fischer that are now disputed, although his style was an obvious influence: