Fröschl initially received his training in his hometown of Augsburg. He later went to Florence to study with Jacopo Ligozzi. He then worked for the Medici in Pisa and Florence until he finally accepted employment as a miniature painter at the court of Rudolf II in Prague in 1603. Fröschl became known primarily for his miniature copies of works by Michelangelo, Correggio and Dürer. He also illustrated scientific works.