Benjamin is a scion of the secondary, Parisian Rothschild dynasty. He is the son of Nadine Lhopitalier, a French Actress and author who converted to Judaism, and Edmond Adolphe de Rothschild, a Swiss banker of Jewish descent. His paternal grandparents were the French banker Maurice de Rothschild (1881–1957) and his first wife, the Swiss Baroness, Noémie Halphen (1888–1968). Noémie Halphen was the granddaughter of financier Eugène Péreire of the Sephardic-Jewish Péreire family of Portugal who were banking rivals of the Rothschilds.
After the death of his Father in 1997, he became chairman of the Benjamin & Edmond de Rothschild group, today named Edmond de Rothschild Group. The Edmond de Rothschild Group has a presence in many financial sectors, including private banking, asset management, fund management and advisory services Business. Benjamin de Rothschild is Chairman of the board of the Edmond de Rothschild group, Chairman of the board of Compagnie Financière Edmond de Rothschild, Chairman of the board of the CBR, Compagnie Benjamin de Rothschild SA, and Chairman of the board of the private bank Banque privée Edmond de Rothschild SA Genève.
Benjamin de Rothschild is a sailing enthusiast, following a family tradition. In 2001, he founded the Gitana Team, a Sports team dedicated to sailing. Captains who joined the team include Loïck Peyron and Lionel Lemonchois.
In 2010, Baron Rothschild estimated his own personal fortune to be around 4 billion euros (US$6 billion). However, of the businesses he manages he stated, "it is difficult to know or even to estimate the worth... In any case nothing is for sale."