Gottfried Bernhard was the eldest surviving son of Gerard and Maria (née Coesfelt) van Swieten. After distinguishing himself in his academic work, Swieten embarked on a notable diplomatic career. Beginning as an assistant to Count Cobenzl in Brussels in 1755, Swieten travelled extensively throughout Europe as a representative of the Habsburg court. In 1777, he returned to Vienna where, like his father before him, he was appointed Imperial Court Librarian and in 1781, was made head of the Studien Hofkommission, one of the most politically powerful positions at court. With the ascent of Leopold II to the Austrian throne in 1791, Swieten was dismissed from the Hofkommission, but retained his position as court librarian until his death in 1803.