Shackleton returned to the lecture circuit and published his own account of the Endurance expedition, South, in December 1919. In 1920, tired of the lecture circuit, Shackleton began to consider the possibility of a last expedition. He thought seriously of going to the Beaufort Sea area of the Arctic, a largely unexplored region, and raised some interest in this idea from the Canadian government. With funds supplied by former schoolfriend John Quiller Rowett, he acquired a 125-ton Norwegian sealer, named Foca I, which he renamed Quest.
The plan changed; the destination became the Antarctic, and the project was defined by Shackleton as an "oceanographic and sub-antarctic expedition". The goals of the venture were imprecise, but a circumnavigation of the Antarctic continent and investigation of some "lost" sub-Antarctic islands, such as Tuanaki, were mentioned as objectives.
Rowett agreed to finance the entire expedition, which became known as the Shackleton–Rowett Expedition. On 16 September 1921, Shackleton recorded a farewell address on a sound-on-film system created by Harry Grindell Matthews, who claimed it was the first "talking picture" ever made. The expedition left England on 24 September 1921.
Although some of his former crew members had not received all their pay from the Endurance expedition, many of them signed on with their former "Boss". When the party arrived in Rio de Janeiro, Shackleton suffered a suspected heart attack. He refused a proper medical examination, so Quest continued south, and on 4 January 1922, arrived at South Georgia.
In the early hours of the next morning, Shackleton summoned the expedition's physician, Alexander Macklin, to his cabin, complaining of back pains and other discomfort. According to Macklin's own account, Macklin told him he had been overdoing things and should try to "lead a more regular life", to which Shackleton answered: "You are always wanting me to give up things, what is it I ought to give up?" "Chiefly alcohol, Boss," replied Macklin. A few moments later, at 2:50 a.m. on 5 January 1922, Shackleton suffered a fatal heart attack.
Macklin, who conducted the postmortem, concluded that the cause of death was atheroma of the coronary arteries exacerbated by "overstrain during a period of debility". Leonard Hussey, a veteran of the Imperial Trans-Antarctic expedition, offered to accompany the body back to Britain; while he was in Montevideo en route to England, a message was received from Emily Shackleton asking that her husband be buried in South Georgia. Hussey returned to South Georgia with the body on the steamer Woodville, and on 5 March 1922, Shackleton was buried in the Grytviken cemetery, South Georgia, after a short service in the Lutheran church, with Edward Binnie officiating. Macklin wrote in his diary: "I think this is as 'the Boss' would have had it himself, standing lonely in an island far from civilisation, surrounded by stormy tempestuous seas, & in the vicinity of one of his greatest exploits."
Study of diaries kept by Eric Marshall, medical officer to the 1907–09 expedition, suggests that Shackleton suffered from an atrial septal defect ("hole in the heart"), a congenital heart defect, which may have been a cause of his health problems.
Shackleton's will was proven in London on 12 May 1922. Dying heavily in debt, Shackleton's small estate consisted of personal effects to the value of £556 2s. 2d. (equivalent to £30,590 in 2019) which he bequeathed to his wife. Lady Shackleton survived her husband by 14 years, dying in 1936.
On 27 November 2011, the ashes of Frank Wild were interred on the right-hand side of Shackleton's gravesite in Grytviken. The inscription on the rough-hewn granite block set to mark the spot reads: "Frank Wild 1873–1939, Shackleton's right-hand man."
Before the return of Shackleton's body to South Georgia, there was a memorial service held for him with full military honours at Holy Trinity Church, Montevideo, and on 2 March a service was held at St Paul's Cathedral, London, at which the King and other members of the royal family were represented. Within a year the first biography, The Life of Sir Ernest Shackleton, by Hugh Robert Mill, was published. This book, as well as being a tribute to the explorer, was a practical effort to assist his family; Shackleton died some £40,000 in debt (equivalent to £2,200,324 in 2019) A further initiative was the establishment of a Shackleton Memorial Fund, which was used to assist the education of his children and the support of his mother.
During the ensuing decades Shackleton's status as a polar hero was generally outshone by that of Captain Scott, whose polar party had by 1925 been commemorated on more than 30 monuments in Britain alone, including stained glass windows, statues, busts and memorial tablets. A statue of Shackleton designed by Charles Sargeant Jagger was unveiled at the Royal Geographical Society's Kensington headquarters in 1932, but public memorials to Shackleton were relatively few. The printed word saw much more attention given to Scott—a forty-page booklet on Shackleton, published in 1943 by OUP as part of a "Great Exploits" series, is described by cultural historian Stephanie Barczewski as "a lone example of a popular literary treatment of Shackleton in a sea of similar treatments of Scott". This disparity continued into the 1950s.
In 1959, Alfred Lansing's Endurance: Shackleton's Incredible Voyage was published. This was the first of a number of books about Shackleton that began to appear, showing him in a highly positive light. At the same time, attitudes towards Scott were gradually changing as a more critical note was sounded in the literature, culminating in Roland Huntford's 1979 treatment of him in his dual biography Scott and Amundsen, described by Barczewski as a "devastating attack". This negative picture of Scott became accepted as the popular truth as the kind of heroism that Scott represented fell victim to the cultural shifts of the late twentieth century.
Within a few years, he was thoroughly overtaken in public esteem by Shackleton, whose popularity surged while that of his erstwhile rival declined. In 2002, in a BBC poll conducted to determine the "100 Greatest Britons", Shackleton was ranked 11th while Scott was down in 54th place.
In 2001 Margaret Morrell and Stephanie Capparell presented Shackleton as a model for corporate leadership in their book Shackleton's Way: Leadership Lessons from the Great Antarctic Explorer. They wrote: "Shackleton resonates with executives in today's business world. His people-centred approach to leadership can be a guide to anyone in a position of authority". Other management writers soon followed this lead, using Shackleton as an exemplar for bringing order from chaos. In 2017 Nancy Koehn argued that, in spite of Shackleton's mistakes, financial problems and narcissism, he developed the capability to be successful.
The Centre for Leadership Studies at the University of Exeter offers a course on Shackleton, who also features in the management education programmes of several American universities. In Boston, a "Shackleton School" was set up on "Outward Bound" principles, with the motto "The Journey is Everything". Shackleton has also been cited as a model leader by the US Navy, and in a textbook on Congressional leadership, Peter L Steinke calls Shackleton the archetype of the "nonanxious leader" whose "calm, reflective demeanor becomes the antibiotic warning of the toxicity of reactive behaviour". In 2001, the Athy Heritage Centre-Museum, Athy, County Kildare, Ireland, established the Ernest Shackleton Autumn School, which is held annually, to honour the memory of Ernest Shackleton.
Shackleton's death marked the end of the Heroic Age of Antarctic Exploration, a period of discovery characterised by journeys of geographical and scientific exploration in a largely unknown continent without any of the benefits of modern travel methods or radio communication. In the preface to his 1922 book The Worst Journey in the World, Apsley Cherry-Garrard, one of Scott's team on the Terra Nova Expedition, wrote: "For a joint scientific and geographical piece of organisation, give me Scott; for a Winter Journey, Wilson; for a dash to the Pole and nothing else, Amundsen: and if I am in the devil of a hole and want to get out of it, give me Shackleton every time".
In 1993 Trevor Potts re-enacted the Boat Journey from Elephant Island to South Georgia in honour of Sir Ernest Shackleton, totally unsupported, in a replica of the James Caird. In 2002, Channel 4 produced Shackleton, a TV serial depicting the 1914 expedition with Kenneth Branagh in the title role. Broadcast in the United States on the A&E Network, it won two Emmy Awards.
In a Christie's auction in London in 2011, a biscuit that Shackleton gave "a starving fellow traveller" on the 1907–1909 Nimrod expedition sold for £1250. That same year, on the date of what would have been Shackleton's 137th birthday, Google honored him with a Google Doodle. Asteroid 289586 Shackleton, discovered by Swiss amateur astronomer Michel Ory in 2005, was named in his memory. The official naming citation was published by the Minor Planet Center on 10 December 2011 (M.P.C. 77510).
In January 2013, a joint British-Australian team set out to duplicate Shackleton's 1916 trip across the Southern Ocean. Led by explorer and environmental scientist Tim Jarvis, the team was assembled at the request of Alexandra Shackleton, Sir Ernest's granddaughter, who felt the trip would honour her grandfather's legacy. In October 2015, Shackleton's decorations and medals were auctioned; the sale raised £585,000. This team became the first to replicate the so-called "double crossing"; sailing from Elephant Island to South Georgia, and the crossing of the South Georgian mountains from King Haakon Bay (where Shackleton had landed nearly 100 years prior) to Stromness.
The expedition very carefully matched legacy conditions, using a replica of the James Caird (named for the project's patron: the Alexandra Shackleton), period clothing (by Burberry), replica rations (both in calorific content and rough constitution), period navigational aids, and a Thomas Mercer chronometer just as Shackleton had used. This expedition was made into a documentary film, screening as Chasing Shackleton on PBS in the United States, and Shackleton: Death or Glory elsewhere on the Discovery Channel.
In 2016 a statue of Shackleton by Mark Richards was erected in Athy, sponsored by Kildare County Council. In 2017, the musical play Ernest Shackleton Loves Me by Val Vigoda and Joe DiPietro made its debut in New York City at the Tony Kiser Theater, an Off-Broadway venue. Blended with a parallel story of a struggling composer, the play retells the adventure of Endurance in detail, incorporating photos and videos of the journey.