Benjamin Harrison VI trained in commerce with the Philadelphia firm of Willing and Morris and developed a lasting connection with Robert Morris. He then traveled in Europe, building mercantile contacts before returning to Virginia during the revolutionary crisis. He was distinct from his father, the Declaration signer and governor.

During the Revolution Harrison served as deputy paymaster general in Virginia, handling funds intended for the Continental Army. Congressional warrants document the transfer of money to his department: in May 1779 Congress ordered $300,000 sent through the Board of War's paymaster, with Harrison accountable for its use. The work required the receipt, distribution and accounting of military money at a time of severe financial strain. His war service was financial administration.

After the war Harrison operated as a Richmond merchant and acquired substantial wealth, although family finances later became troubled. He remained close to Morris and supplied assistance when the financier faced difficulties. In the 1790s he took over Berkeley, the family's James River plantation, and oversaw alterations to its house, including fashionable Adam-style interior work and the arches between its principal rooms. Its income depended on enslaved labor. Harrison died in 1799, leaving Berkeley to another generation. His short career combined Atlantic commerce, wartime financial administration and the management of an inherited Virginia estate.