Director of the Frankfurt banking firm Gebrüder Bethmann.
Took over his uncle’s mercantile firm (1746) and, with his brother Simon Moritz, converted it into the firm Gebrüder Bethmann (1748). Shifted firm’s focus from trade to money- changing and the arrangement of loans to German princes. Patron of hospitals and other social welfare projects.
Son of Simon Moritz and Elisabeth (Thielen) Bethmann. Married Elisabeth Rummel in 1752. Married Katherine Margareta Elisabeth Schaaff in 1762; two children.