Hevelius was born and educated in Danzig (now Gdańsk). He spent some time in Leiden, London, and Paris before settling down in Danzig, where he worked as a brewing merchant and was a city councillor. He spent his evenings on the roof of his house, where he had an observatory installed 1641, and furnished it with instruments of his own construction. He built a number of telescopes using long focal lengths to avoid chromatic aberration, his largest being a tubeless instrument 46 m/150 ft long. Although he used telescopes for details of the Moon and planets, he refused to apply them to his measuring apparatus. His observations of the positions of stars were made with the naked eye, and were more accurate than those of the Danish astronomer Tycho Brahe.

In the period 1642-45 Hevelius deduced a fairly accurate value for the period of the solar rotation, and gave the first description of the bright areas in the neighbourhood of sunspots. The name he gave to them, faculae, is still used.

The observatory was destroyed by fire 1679, with some of his notes.