From 1924 to 1926, Auchincloss practiced law in New York City, before joining the Commerce Department as a special agent in aeronautics. In 1927, he was appointed an aviation expert in the State Department. Four years later in 1931, he resigned government service to form a brokerage firm. In 1931, he bought his seat on the New York Stock Exchange for $235,000. It was reported that he used some of the large inheritance received from his mother to found the Washington, DC brokerage firm of "Auchincloss, Parker & Redpath" with Chauncey B. Parker and Albert G. Redpath. The firm eventually had 16 offices with two in New York City and the rest spread along the East Coast. In 1970, the firm merged with Thomson & McKinnon, a brokerage house based in New York. At the time of the merger, the new firm, known as Thomson & McKinnon Auchincloss, had assets of $160 million and 58 offices. By the time of his Auchincloss' death in 1976, the firm was known as Thomson & McKinnon Auchincloss Kohlmeyer. During World War II Auchincloss worked for the Office of Naval Intelligence and the War Department and was commissioned with the rank of Lieutenant in the Naval Reserve on May 26, 1942, serving in the United States Navy during World War II.
Personal life
Auchincloss was married three times and had five children. His first marriage was on June 4, 1925 to Maya de Chrapovitsky, a Russian noblewoman. Before their divorce in 1932, they had one child together:
Hugh Dudley "Yusha" Auchincloss III
In 1935, he married Nina S. Vidal, the only daughter of Senator Thomas Gore. Nina had previously been married to Eugene Vidal, a Roosevelt appointee, and with him had Gore Vidal, the author. Before their divorce in 1941, they had two children:
On June 21, 1942, he married for the third and final time to Janet Lee Bouvier, mother of Jacqueline Kennedy Onassis and Lee Radziwill. They remained married until his death in 1976 and had two children together:
Auchincloss was responsible for getting Jacqueline Bouvier her first job in journalism at the Washington Times-Herald. He gave her away at her wedding to future president John F. Kennedy, the reception of which was held at Hammersmith Farm on September 12, 1953. A long-time financial contributor to the Republican Party, he contributed to the campaign of his Democratic stepson-in-law, saying "I want to live in harmony with Mrs. Auchincloss and all the other members of the family." Auchincloss died at his home in Georgetown on November 20, 1976 and was later buried at Island Cemetery in Newport.