Homann was born in Oberkammlach near Kammlach, which is now in Bavaria. Although educated at a Jesuit school, he eventually converted to Protestantism. In 1715 Homann was appointed Imperial Geographer of the Holy Roman Empire. Giving such privileges to individuals was an added right that the Holy Roman Emperor enjoyed. In the same year he was also named a member of the Prussian Academy of Sciences. Of particular significance to cartography were the imperial printing privileges (Latin privilegia impressoria). These protected for a time the authors in all scientific fields such as printers, copper engravers, map makers and publishers. They were also very important as recommendation for potential customers.
In 1716 Homann published his masterpiece Grosser Atlas ueber die ganze Welt (Grand Atlas of all the World).
Homann died in Nuremberg. He was succeed by the Homann heirs company, in business until 1848, known as "Homann Erben", "Homannianos Heredes", "Heritiers de Homann" abroad.