In 1857, in London, he married Baroness Leonora von Rothschild (1837-1911), the daughter of Lionel Nathan Rothschild (1808-1879) and Charlotte Rothschild (1819-1884). They had the following children:
In 1885, Nathan Mayer Rothschild II (1840-1915) of the London branch of the family, was granted the peerage title Baron Rothschild in the Peerage of the United Kingdom.
James' sons Gustave deRothschild and AlphonseJamesdeRothschild continued the banking tradition and were responsible for raising the money to pay the compensation demanded by the occupying Prussian army in the 1870s Franco-Prussian War.
Hannah Primrose, Countess of Rosebery nee Hannah Rothschild (1851-1890)