In 2011, Hilton began dating financier James Rothschild (born 1985), a member of the Rothschild family and only son of Amschel Rothschild. On August 12, 2014, Hilton became engaged to Rothschild. On July 10, 2015, the couple married at The Orangery in Kensington Palace Gardens in London, England.

In 2026, the connection between the Hilton and Rothschild families is one of high-profile marriage rather than shared ancestry. The link was established on July 10, 2015, when Nicky Hilton, the great-granddaughter of Hilton Hotels founder Conrad Hilton, married James Rothschild, a member of the storied European banking dynasty. This union brought together two of the world's most famous names in hospitality and finance. The couple met in 2011 at a wedding in Italy and currently have three children, who represent the direct genealogical intersection of these two influential lineages. While the Hilton family is primarily associated with the global hotel empire and the Rothschilds with centuries of international banking and viticulture, their relationship today is a modern fusion of American industrial royalty and European nobility. Despite the marriage, the Hilton Worldwide corporation remains a separate business entity from the various Rothschild family holdings and investment firms.