Gutenberg was born in the German city of Mainz, the youngest son of the upper-class merchant Friele Gensfleisch zur Laden, and his second wife Else Wyrich, who was the daughter of a shopkeeper. According to some accounts Friele was a goldsmith for the bishop at Mainz, but most likely he was involved in the cloth trade. Gutenberg's year of birth is not precisely known but was most likely around 1398.

In 1411, there was an uprising in Mainz against the patricians, and more than a hundred families were forced to leave. As a result, the Gutenbergs are thought to have moved to Eltville am Rhein (Alta Villa), where his mother had an inherited estate. According to historian Heinrich Wallau, All that is known of his youth is that he was not in Mainz in 1430. It is presumed that he migrated for political reasons to Strasburg, where the family probably had connections. He is assumed to have studied at the University of Erfurt, where there is a record of a student, in 1419, named Johannes de Alta villa.
Nothing is now known of Gutenberg's life for the next fifteen years, but in March 1434, a letter by him indicates that he was living in Strasbourg, where he had some relatives on his mother's side. He also appears to have been a goldsmith member enrolled in the Strasbourg militia. In 1437, there is evidence that he was instructing a wealthy tradesman on polishing gems, but where he had acquired this knowledge is unknown. In 1436/37 his name also comes up in court in connection with a broken promise of marriage to a woman from Strasbourg, Ennelin. Whether the marriage actually took place is not recorded. Following his father's death in 1419, he is mentioned in the inheritance proceedings.