Elliott Roosevelt was the fourth of Franklin and Eleanor's six children, their third child having died in infancy about a year before Elliott's birth. Roosevelt was named after his maternal grandfather, Elliott Roosevelt. His siblings who reached adulthood were:

• Anna Eleanor Roosevelt (later Dall, Boettiger, Halsted)
• James Roosevelt
• Franklin Roosevelt
• John Aspinwall Roosevelt

Roosevelt attended Groton School like his brothers but did not continue on to Harvard University. Instead, he worked a series of jobs, finally settling in communications in the 1930s, including a management position in the Hearst radio chain.

Roosevelt enlisted in the United States Army Air Corps in 1940. He served as a pilot and unit commander in the United States Army Air Forces (USAAF) during World War II.

In January 1943, Roosevelt accompanied FDR as a military attaché to the Casablanca meeting and the subsequent Cairo and Tehran Conferences. At the Tehran Conference, Elliot Roosevelt, apparently under the influence of alcohol, sided with his father in approving of large-scale executions of German POWs by the Soviets..

Roosevelt commanded the following units:

• 3d Reconnaissance Group, 11 July—13 August 1942 at the rank of major; 30 September 1942—1 March 1943 ending at the rank of colonel

Assigned to Twelfth Air Force and flew P-38 Lightning (F-5) photographic reconnaissance missions during the North Africa campaign in Algeria and Tunisia

• 90th Reconnaissance Wing, 22 November 1943—25 January 1944 at the rank of colonel

Assigned to Twelfth Air Force, command and control organization that provided photographic reconnaissance to both Twelfth and Fifteenth Air Forces. Operationally controlled both 3d and 5th Reconnaissance Groups in Tunisia. The 90th's subordinate units reconnoitered airdromes, roads, marshaling yards, and harbors in Italy after the Allied landings at Salerno.

• 325th Reconnaissance Wing, 9 August 1944—17 January 1945 at the rank of colonel; 22 January—13 April 1945 ending at the rank of brigadier general

Assigned to Eighth Air Force, command and control organization that through subordinate units, flew reconnaissance over the waters adjacent to the British Isles and the European continent to obtain meteorological data. Wing aircraft collected weather information needed in planning operations; flew night photographic missions to detect enemy activity; and provided daylight photographic and mapping missions. The wing also flew photographic missions over the Netherlands in support of Operation Market Garden in September 1944 and operated closely with tactical units in the Battle of the Bulge (December 1944—February 1945).

Roosevelt flew 300 combat missions. His decorations included the Distinguished Flying Cross. As a chase pilot for the Operation Aphrodite flights in 1944, he witnessed the death of Joseph P. Kennedy, Jr. over Blythburgh, England.

Warplanes purchasing scandal

In August 1943, Colonel Roosevelt was asked by General of the Army Air Forces Henry H. "Hap" Arnold to select among several potential photo reconnaissance aircraft under development to determine a successor to the high-flying and fast camera carriers then in use, though the reason for Arnold's choice of Roosevelt was not made public. Roosevelt assembled a group of five air officers including veteran RAF reconnaissance pilot Flight Lieutenant D. W. Stevenson. Upon their arrival in Los Angeles Roosevelt and his group were met by eight limousines arranged by John W. Meyer, a publicist and former nightclub owner who was employed by Hughes Aircraft. On his first day in town, Roosevelt was taken by Meyer to the Hollywood film studio of Warner Bros. and introduced to Faye Emerson, an actress with whom Roosevelt was soon linked romantically. Over the next three days, Roosevelt and his group were seen with Meyer in Hollywood nightclubs and at parties in luxurious mansions in the company of aspiring actresses paid $100—400 per night by Meyer, the higher figure equivalent to $}} in current value. On August 11, Howard Hughes showed the group his Culver City operation, then personally flew them to see the Hughes D-2, an experimental twin-engine, wooden reconnaissance aircraft being assembled at a Hughes facility in the Mojave Desert. The aircraft had already been turned down ten months earlier by Chief of Army Air Forces Material Division, Oliver P. Echols, for being inadequate to military service; it was not judged powerful enough for the increased weight it would have after being constructed out of metal per AAF requirements. Roosevelt and the group of aviators, however, expressed appreciation for the D-2. When Roosevelt returned to the East Coast, Meyer hosted another round of parties and nightclub outings in Manhattan, and arranged for Fay Emerson to accompany Roosevelt. Meyer gave Emerson $132 worth of nylon stockings, a rare treat during wartime rationing.

On August 20, Roosevelt sent a report to General Arnold recommending immediate purchase of the D-2. On September 1, Arnold ordered Echols to contract with Hughes for an all-metal reconnaissance aircraft "against my better judgment and the advice of my staff." Major General Charles E. Bradshaw wrote to Arnold to suggest that the Lockheed XP-58 Chain Lightning was much farther along in development and could outperform the D-2 in every important aspect, but was unsuccessful in halting the Hughes contract. Implicating Roosevelt and United States Secretary of Commerce Jesse H. Jones, Assistant Secretary of War Robert A. Lovett noted to Major General Bennett E. Meyers that "Hughes has got powerful friends here in Washington" and that, if the background of the contract were uncovered, "there's going to be an awful smell." Nonetheless, Hughes was given $43 million (worth $}} million today) to build 100 all-metal aircraft, to be designated the Hughes XF-11.

In 1947, Roosevelt telephoned Hughes to warn him that a Senate subcommittee intended to call them both to account for financial irregularities regarding the XF-11 as well as for Hughes's H-4 Hercules, also known as the "Spruce Goose". As part of the ongoing "Investigation of the National Defense Program", on August 4, 1947 the subcommittee called Roosevelt and Meyer to testify about the Hollywood and Manhattan parties and women that Meyer had arranged and paid for. Meyer's financial records during such parties showed him paying $200 for "presents for four girls" and $50 for "girls at hotel (late)." At one point, Roosevelt asked Meyer whether "any of those girls who were paid, were they procured for my entertainment?" Meyer responded "I don't like the word 'procured,' because a girl who attends a party and is given a present is not necessarily 'procured.' " The committee found that Meyer had spent at least $1,000 in picking up Roosevelt's hotel bills as well as his nightclub and party checks, and Faye Emerson's bets at Agua Caliente Racetrack, and that Meyer had arranged for weekends in Palm Springs and Washington, D.C. for Roosevelt and Emerson, who eventually married in December 1944 after Roosevelt divorced his second wife in March 1944. All told, Meyer reported to the committee that he had spent $5,083.79 ($}} in today's dollars) on entertainment for Roosevelt. In his own defense, Roosevelt testified that he had never heard of the XF-11 until "Hap" Arnold let him know about it, and that several of the parties appeared to have taken place on days when he was out of the country on active duty. Roosevelt said "If it is true that for the price of entertainment I made recommendations which would have in any way endangered the lives of the men under me . . . that fact should be made known to the public."

After FDR's death in 1945, Roosevelt and his family moved to Top Cottage to be near his mother, who considered Roosevelt her favorite child. She gave him financial assistance throughout her life. In 1947 she bought from the FDR estate Val-Kill farms, the home she lived in after FDR's death, and deeded the property to Roosevelt. In 1952, Roosevelt's brother John bought the tract. Later, the property became Eleanor Roosevelt National Historic Site.

Roosevelt pursued many different careers during his life, including owning a radio station in Texas and living as a rancher. He raised Arabian horses in Portugal, then served from 1964 to 1969 as the mayor of Miami Beach, Florida. As Roosevelt approached his eightieth year of age, his final ambition was to "outlive James." However, Roosevelt died at age 80 of congestive heart failure. His brother James Roosevelt survived Roosevelt by one year.

He was also the author of numerous books, including a mystery series in which his mother, Eleanor Roosevelt, is the detective.

Roosevelt described his experiences with his father during five important war conferences in his best-selling book As He Saw It.

Together with James Brough, Roosevelt wrote a highly personal book about his parents called The Roosevelts of Hyde Park: An Untold Story where he reveals details about the sexual lives of his parents, including his father's unique relationships with mistress Lucy Mercer and secretary Marguerite LeHand as well as graphic details surrounding the illness that crippled his father. The biography also contains valuable insights into FDR's run for vice-president, rise to the governorship of New York, and his capture of the presidency in 1932, particularly with the help of Louis Howe.A sequel to the "An Untold Story" with James Brough was published in 1975, titled "A Rendezvous With Destiny" carried the Roosevelt saga to the end of WWII.

Roosevelt was married five times:

• On January 16, 1932 he married Elizabeth Browning Donner, daughter of William Henry Donner. They had one son, William Donner Roosevelt, in 1932. The marriage ended in divorce in 1933. She died in 1980.
• On July 22, 1933, in Burlington, Iowa, he married Ruth Josephine Googins (Ruth G. Eidson). They had three children: Ruth Chandler Roosevelt (Lindsley) (b. 1934), Elliott "Tony" Roosevelt Jr. (b. 1936), and David Boynton Roosevelt (b. 1942). Roosevelt and Ruth were divorced in March 1944. Ruth Googins Roosevelt Eidson died in 1974.
• On December 3, 1944, at the Grand Canyon in Arizona, he married actress Faye Emerson. They were divorced on January 17, 1950. She died of stomach cancer in 1983 in Spain.
• On March 15, 1951, at Miami Beach, Florida, he married Minnewa Bell (Gray Burnside Ross). They were divorced in 1960. Minnewa died in 1983.
• On November 3, 1960, at Qualicum Beach, British Columbia, Canada, he married Patricia Peabody Whitehead. Her four children, James M. Whitehead, Ford Whitehead, Gretchen Whitehead and David Macauley Whitehead, all adopted Roosevelt as their surname. The couple's only child together, Livingston Delano Roosevelt, died in 1962 as an infant.