Socialite. Astor's parents had married on September 9, 1911 and were returning home aboard the Titanic after about three months of honeymooning in Egypt and Europe. Madeleine Astor was five months pregnant when her husband put her in one of Titanic's lifeboats. She was rescued eight hours after her husband went down with the ship. The younger Astor is by some considered a Titanic survivor, albeit in utero.

Under the terms of her husband's will, Madeleine Astor received relatively little from an estate estimated to be as much as $100 million. Provided she did not remarry, the 19-year-old widow received the annual investment income from a $5 million-dollar trust fund and the use of her late husband's homes on Fifth Avenue in New York City and in Newport, Rhode Island. No specific provision for the unborn child had yet been made, but a clause of his father's will provided that any surviving child other than his son Vincent and his daughter Ava would receive a bequest of $3 million, to be held in trust until the child reached age 21.This amount eventually went to the younger Astor on his 21st birthday, which by then the sum had grown to $5 million.

His stepfathers were William K. Dick and Enzo Fiermonte.

John Jacob Astor VI graduated from St. George's School in Newport, Rhode Island.

Astor was originally engaged to Eileen S.S. Gillespie, daughter of Mr. and Mrs. Lawrence Lewis Gillespie of New York City and Newport, Rhode Island in December 1933. However, she broke off the engagement two days before the wedding; reportedly, "She felt that he had grown up lonely … He was a bit eccentric, and she felt he wasn't mature enough to get married."

He married Ellen Tuck French at Trinity Church in Newport, Rhode Island on June 30, 1934. The couple was divorced in 1943; they had one child, William Astor.

Astor then married Gertrude Gretsch, daughter of Walter Gretsch, in New York City on September 18, 1944. The couple had a daughter, Mary Jacqueline (born 1949), but their marriage ended in divorce in 1954, though the Mexican divorce was ruled invalid in 1956. An American divorce soon followed. Gertrude Astor remarried, in 1961, to Sonio Coletti-Perucca.

He married a third time to Dolores Margaret Fullman (born 1929) on 6 August 1954 but they separated soon after returning from their honeymoon and divorced.

His fourth wife was Sue Sandford; she predeceased him, circa 1989.

John Jacob Astor VI had one son from the 1st, and one daughter from the 2nd marriage:
William Astor (born 1935), married Charlotte Fisk. They had 2 children: William Backhouse Astor IV (born 1959) and G. Todd Astor (born 1966), who has three children: Alexandra Astor, Rebecca Astor and Stephen Astor. William Astor died on September 24, 2008.
Jacqueline Astor (born 1949), married in 1984 to John R Drexel IV (born 1945) and they had one son, Nicholas.

John Jacob Astor VI died in Miami Beach, Florida in 1992 at the age of 79. His body was returned to New York for burial with his parents in the Trinity Church Cemetery.

John Astor