Chalabi was the son of a prominent Shi'a family, one of the wealthy power elite of Baghdad. He was born at Kadhimiya in 1944. His family, who dated back 300 years to the Sultanate ran Iraq’s oldest commercial bank under the British-backed Kingdom of Iraq. His father was a wealthy grain merchant and member of the Iraqi parliament, became head of the senate when King Abdullah was assassinated.

His family retired from public life to a farmhouse near Baghdad when the military seized power. Chalabi left Iraq with his family in 1958, following the 14 July Revolution, and spent most of his life in the United States and the United Kingdom. He was educated at Baghdad College and Seaford College in Sussex, England before leaving for America.

In 1971, Chalabi married Leila Osseiran, daughter of Lebanese Politician Adil Osseiran. They had four children. Whilst still at Beirut the civil war broke out in 1975, so he moved to Jordan and found work as an interpreter.

Chalabi was a bold and shrewd investor, amassing a fortune of $100 million. During his life he was accused of corruption many times. In 1977, he founded the Petra Bank in Jordan with Crown Prince Hassan, the King's brother. In May 1989, the Governor of the Central Bank of Jordan, Mohammed Said Nabulsi, issued a decree ordering all banks in the country to deposit 35% of their reserves with the Central Bank. Petra Bank was the only bank that was unable to meet this requirement. An investigation was launched which led to accusations of embezzlement and false accounting. The bank failed, causing a $350 million bail-out by the Central Bank. Chalabi fled the country, in the boot of a Jordanian prince's car, before the authorities could react. Chalabi was convicted and sentenced in absentia for bank fraud by a Jordanian military tribunal to 22 years in prison. Chalabi maintained that his prosecution was a politically motivated effort to discredit him sponsored by Saddam Hussein.

Chalabi headed the executive council of the INC, an umbrella Iraqi opposition group created in 1992 for the purpose of fomenting the overthrow of Saddam Hussein. The INC received major funding and assistance from the United States. Chalabi was involved in organizing a resistance movement among Kurds in northern Iraq in the early mid-1990s. When that effort was crushed and hundreds of his supporters were killed, Chalabi fled the country. Chalabi lobbied in Washington for the passage of the Iraq Liberation Act (passed October 1998). This earmarked US$97 million to support Iraqi opposition groups. But in 2001 it was revealed that INC was accused of false accounting and irregularities. During the period from March 2000 to September 2003, the U.S. State Department paid nearly $33 million to the INC, according to a General Accounting Office report released in 2004,some of which was used to purchase office artefacts.

In 1995 after preparation and lobbying he persuaded President Clinton to fund an expedition into northern Iraq to use subterfuge to start an insurgency. Chalabi was convinced that the Iraqi military would rise up to usurp the dictator. The commanders to whom he had spoken, were the same who openly supported Saddam and crushed his opponents in the Kurdish and Shi'ite revolts. The insurgency failed, lacked the promised ground troops, and 100 insurgents were killed by the military. The command structure of INC fell apart with factional infighting. Chalabi was banned from those frequent visits to CIA HQ at Langley, Virginia. Nonetheless Chalabi was doggedly determined: in 1998 Congress passed the Iraqi Liberation Act making it American law that "regime change" would happen in Iraq.

The INC often worked with the media, most notably with Judith Miller, concerning her WMD stories for The New York Times starting on 26 February 1998. After the war, given the lack of discovery of WMDs, most of the WMD claims of the INC were shown to have been either misleading, exaggerated, or completely made up while INC information about the whereabouts of Saddam Hussein's loyalists and Chalabi's personal enemies were accurate. Another of Chalabi's advocates was American Enterprise Institute's Iraq specialist Danielle Pletka. Chalabi received advice on media and television presentation techniques from the Irish scriptwriter and commentator Eoghan Harris prior to the invasion of Iraq.

In August 2003, Chalabi was the only candidate whose unfavorable ratings exceeded his favorable ones with Iraqis in a State Department poll. In a survey of nearly 3,000 Iraqis in February 2004 (by Oxford Research International, sponsored by the BBC in the United Kingdom, ABC in the U.S., ARD of Germany, and the NHK in Japan), only 0.2 percent of respondents said he was the most trustworthy leader in Iraq (see survey link below, question #13). A secret document written in 2002 by the British Overseas and Defence Secretariat reportedly described Chalabi as "a convicted fraudster popular on Capitol Hill."

On 1 September 2004, Chalabi told reporters of an assassination attempt made on him near Latifiya, a town south of Baghdad. Chalabi reported he was returning from a meeting with Ayatollah Ali al-Sistani (whose trust Chalabi enjoyed) in Najaf, where a few days earlier a cease-fire had taken effect, ending three weeks of confrontations between followers of Muqtada al-Sadr and the U.S. military, at the time.

Prior to the December 2005 elections, the Iraqi National Congress had left the United Iraqi Alliance and formed the National Congress Coalition, which ran in the elections but failed to win a single seat in Parliament, gaining less than 0.5% of the vote. Other groups joining the INC in this list included: Democratic Iraqi Grouping, Democratic Joint Action Front, First Democratic National Party, Independent List, Iraqi Constitutional Movement, Iraqi Constitutional Party, Tariq Abd al-Karim Al Shahd al-Budairi, and the Turkoman Decision Party. He was refused a seat in the cabinet. Dogged by allegations, still unproven, of corruption he retorted that he had never "participated in any scheme of intelligence against the United States."

Chalabi attended the 2006 Bilderberg Conference meeting outside of Ottawa, Ontario, Canada. In October 2007, Chalabi was appointed by Prime Minister Nouri al Maliki to head the Iraqi services committee, a consortium of eight Service ministries and two Baghdad municipal posts tasked with the "surge" plan's next phase, restoring electricity, health, education and local security services to Baghdad neighborhoods. "The key is going to be getting the concerned local citizens—and all the citizens—feeling that this government is reconnected with them.... [Chalabi] agrees with that," said Gen. David Petraeus. Chalabi "is an important part of the process," said Col. Steven Boylan, Petraeus' spokesman. "He has a lot of Energy." In April 2008, Journalist Melik Kaylan wrote about Chalabi, "Arguably, he has, more than anyone in the country, evolved a detailed sense of what ails Baghdadis and how to fix things."

After the invasion Chalabi was placed in charge of "de-Ba'athification"—the removal of senior office holders judged to have been close supporters of the deposed Saddam Hussein. The role fell into disuse, but in early 2010 Chalabi was accused of reviving this dormant post to eliminate his political enemies, especially Sunnis. The banning of some 500 candidates prior to the general election of 7 March 2010 at the initiative of Chalabi and his Iraqi National Congress was reported to have badly damaged previously improving relations between Shias and Sunnis.

The CIA was largely skeptical of Chalabi and the INC, but information allegedly from his group (most famously from a defector codenamed "Curveball") made its way into intelligence dossiers used by President George W. Bush and British Prime Minister Tony Blair to justify an invasion of Iraq. "Curveball", Rafid Ahmed Alwan al-Janabi, fed officials hundreds of pages of bogus "firsthand" descriptions of mobile biological weapons factories on wheels and rails. Secretary of State Colin Powell later used this information in a U.N. presentation trying to garner support for the war, despite warnings from German intelligence that "Curveball" was fabricating claims. Since then, the CIA has admitted that the defector made up the story, and Powell said in 2011 the information should not have been used in his presentation. A later congressionally appointed investigation (Robb-Silberman) concluded that Curveball had no relation whatsoever to the INC, and that press reports linking Curveball to the INC were erroneous.

On 26 January 2012, the New York Times reported Western intelligence officials expressing concern that Chalabi was working with the leading opposition group in Bahrain, Al Wefaq National Islamic Society. A French intelligence official said, "When we hear that some members of the opposition are in touch with Hezbollah or with shady figures like the Iraqi Ahmed Chalabi, of whom we think he is acting on behalf of Iran, then this worries us". The connection between Chalabi and Al Wefaq was acknowledged by Jawad Fairooz, secretary general of Wefaq and a former member of Parliament in Bahrain. Fairooz said, "Mr Chalabi has helped us with contacts in Washington like other people have done and we thank them."

He was interim Minister of Oil in Iraq in April–May 2005 and December 2005 – January 2006 and Deputy Prime Minister from May 2005 to May 2006. Chalabi failed to win a seat in parliament in the December 2005 elections, and when the new Iraqi cabinet was announced in May 2006, he was not given a post. Once dubbed the "George Washington of Iraq" by American supporters, he later fell out of favor and came under investigation by several U.S. government sources. He was also the subject of a 2008 biography by investigative Journalist Aram Roston, The Man Who Pushed America to War: The Extraordinary Life, Adventures, And Obsessions of Ahmad Chalabi and a 2011 biography by 60 Minutes Producer Richard Bonin, Arrows of the Night: Ahmad Chalabi's Long Journey to Triumph in Iraq.

During an interview in 2014, he was shown to be frail and depressed about his country's future:

Chalabi died on 3 November 2015, four days after his 71st birthday, having apparently suffered a heart attack at his home in Kadhimiya, Baghdad. When he died, he was a current Member of the Iraqi Parliament, serving as the chairman of the Finance Committee.

In exile, following the Ba'ath party takeover, his family acted as the Iraqi Shia clergy’s Bankers. In the mid-1960s, he studied with cryptographer Whitfield Diffie at the Massachusetts Institute of Technology from which he received a bachelor of science degree in mathematics. In 1969, he earned a Ph.D. in mathematics from the University of Chicago under the direction of George Glauberman on the Theory of Knots. after which he took a position in the mathematics department at the American University of Beirut. He published three mathematics papers between 1973 and 1980, in the field of abstract algebra.