He was born in Weimar. In 1723 his father took a job in Leipzig, partly because of the educational opportunities there for his chidren. He attended the Thomasschule, his father providing for his musical formation. In contrast to his elder brothers Wilhelm Friedemann and Carl Philipp Emanuel he did not get the opportunity to study at the university after finishing school. Instead, he competed for a post as musician.
Johann Gottfried Bernhard first served as organist at the Marienkirche in Mühlhausen in 1735 and, after leaving the town charged with debts, managed with the support of his father to find a new engagement as organist at the Jakobikirche in Sangerhausen.
The organ of St Jacob's
In 1738, he secretly abandoned a career in music in order to study law in Jena. There he died prematurely at aged 24. It is unknown if, like his brothers, Gottfried Bernhard was a composer.