Brown was initially employed in Nicolai Fenwich's trading house in Helsingør.

He purchased a property at Christianshavns Kanal, close to Snorrebroen, where he established a coal storage depot and warehouse.

From 1884, he also began to trade in Danish India with his own ships, especially after his brother was appointed as Lord Governor of Tranquebar.

[1] In 1781, he acquired the dockyard of Unrost at Frederick's German Church in Christianshavn for his eldest son William.

He was the second-largest landowner in Gentofte (after Count Johann Hartwig Ernst von Bernstorff).

In 1782, he purchased the Barchmann Mansion at the corner of Frederiksholms Kanal and Ny Kongensgade in Copenhagen.

He died on the estate on 16 January 1808 and is buried in Applebye's Chapel in Frederick's German Church in Copenhagen.