Ava was born on July 7, 1902 in Manhattan, New York. She was the only daughter of Colonel John Jacob "Jack" Astor IV (1864–1912) and Ava Lowle Willing (1868–1958). Her paternal grandparents were real estate businessman and race horse breeder/owner William Backhouse Astor, Jr. (1829–1892) and socialite Caroline Webster "Lina" Schermerhorn (1830–1908), while her maternal grandparents were businessman Edward Shippen Willing (1822–1906) and socialite Alice Bell Barton (1833–1903).
On July 24, 1924, Ava Astor married Prince Sergei Platonovich "Serge" Obolensky, son of General Platon Sergeyevich Obolensky and Maria Konstantinovna Naryshkina, at Savoy Chapel in London. The marriage was considered the event of the season in England that year. Her brother Vincent gave her a Palladian Revival stone residence on his estate near Rhinebeck, New York. The house was north of his own "Ferncliff Casino" ("Astor Courts") and also overlooked the Hudson River. Ava named it "Marienruh" and retained it through her life. Before divorcing Serge in 1932, they had two children:Prince Ivan Sergeyevich Obolensky (b. 1925)
Princess Sylvia Sergeyevna Obolensky (1931–1997), who first married Jean-Louis Ganshof van der Meersch (1924–1982) in 1950. After their divorce in 1957 without issue, she then in 1957 she married Prince Azamat Kadir Guirey (1924–2001), with whom she had children before divorcing in 1963.
On January 21, 1933, she married Raimund von Hofmannsthal (1906–1974), son of Gertrud Schlesinger and Hugo von Hofmannsthal, an Austrian novelist, librettist, and dramatist. The couple was married in the city court of Newark, New Jersey. Together, the couple had a daughter:Romana von Hofmannsthal (c. 1935–2014), who married Roderick McEwen (1932–1982), son of Sir John McEwen, 1st Baronet.
From 1936–1937, she had an affair with English choreographer Sir Frederick Ashton (1904–1988), despite the fact that he was gay. After the affair ended, her love for him continued, though she had two subsequent marriages, both to gay Englishmen. Ava and Raimund eventually divorced in 1939, and Raimund later married Lady Elizabeth Paget.
On March 27, 1940, she married Philip John Ryves Harding (1906–1972), a journalist, in Faversham, England. At the time of their wedding, Harding, a cousing of Maxwell Eley, was serving with an anti-aircraft battery in the British Army. Before their divorce in 1945, they had one daughter:Emily Edwina Harding (b. 1942)
On May 12, 1946, she had her fourth and final marriage to David Pleydell-Bouverie (b. 1911-1994), the grandson of William Pleydell-Bouverie, 5th Earl of Radnor, in Reading, Vermont. Pleydell-Bouverie was an architect who studied at Charter House College in England. The couple resided in New York City and Glen Ellen, California, before divorcing in 1952.
Astor died of a stroke in her East Sixty-First Street apartment, Manhattan, New York City, on July 19, 1956 at age 54. She predeceased her mother by two years. She was a patron of the arts, including the ballet companies of London and New York City.
Her will was admitted to probate on November 5, 1956, in Manhattan Surrogate Court. Her assets, totaling $5,305,000, (equivalent to approximately $46,732,050 in 2016 dollars) were divided among her four children. At her mother's death in 1958, her children received an additional $2,500,000 (equivalent to approximately $20,752,595 in 2016 dollars)Miss Ava Alice Muriel Astor (July 7, 1902 - July 24, 1924)
Princess Sergei Platonovich Obolensky (July 24, 1924 - 1932)
Princess Alice Obolensky (1932 - January 21, 1933)
Mrs. Raimund von Hofmannsthal (January 21, 1933 - 1939)
Mrs. Alice Astor von Hofmannsthal (1939 - March 27, 1940)
Mrs. Philip John Ryves Harding (March 27, 1940 - 1945)
Mrs. Alice Astor Harding (1945 - May 12, 1946)
Mrs. David Pleydell-Bouverie (May 12, 1946 - 1952)
Mrs. Alice Astor Pleydell-Bouverie (1952 - July 19, 1956)