The Paris-based firm agreed to a $777.8 million in penalty for payments it made to keep a factory running in Syria after war broke out in 2011, reports the BBC.
Prosecutors said it marked the first time a company had pleaded guilty in the US to aiding terrorists.
Lafarge said it “deeply regretted” the events and “accepted responsibility for the individual executives involved”.
The cement manufacturer, which was bought by Switzerland’s Holcim in 2015, said their behaviour had been in “flagrant violation” of Lafarge’s code of conduct.
The firm opened its plant in Jalabiya near the Turkish border in 2010 following a $680 million investment.
US prosecutors said that Lafarge’s Syrian subsidiary had paid the IS and another terror group, Al-Nusra Front, the equivalent of $5.92 million to protect staff at the plant as the country’s civil war intensified. Executives likened the arrangements to paying “taxes”, the BBC reported.
The cement manufacturer eventually evacuated the plant in September 2014, when the IS took control of the town and the factory.
But before its departure, the deals helped the company do $70.3 million in sales, prosecutors said.
Lafarge had previously admitted bribes were paid after an internal investigation.
But US Deputy Attorney General Lisa Monaco said on Tuesday that the company’s actions “reflect corporate crime that has reached a new low and a very dark place”.
“Business with terrorists cannot be business as usual,” the BBC quoted Monaco as saying.
In a statement, Lafarge’s new owner Holcim said none of the conduct involved the multi-national company, “which has never operated in Syria”.
It added that former Lafarge executives involved in the bribery had concealed it from Holcim, as well as external auditors.
Eric Olsen, who was CEO between 2015 and 2017, stepped down from his role following an investigation into Lafarge’s activities in Syria.
Executives had attempted to require IS not to include the name “Lafarge” on documents memorializing and implementing their agreements and many involved in the scheme also used personal email addresses, rather than their corporate email addresses, to carry out the conspiracy, the Department said, BBC reported.
Lafarge executives also backdated the termination agreement to August 18, 2014, a date shortly after the UN Security Council had issued a resolution calling on member states to prohibit doing business with Islamic State, to falsely suggest that negotiations with Islamic State had not occurred after the UN resolution, the Department said.
The dealings by Lafarge were eventually made by public in 2016 on a website run by a Syrian opposition group.
Breon Peace, US Attorney for the Eastern District of New York, where the case was brought, said the conduct “by a Western corporation was appalling, and has no precedent or justification”.
“The defendants paid millions of dollars (to IS), a terrorist group that otherwise operated on a shoestring budget, millions of dollars that (IS) could use to recruit members, wage war against governments, and conduct brutal terrorist attacks worldwide, including against US citizens,” he said at a press conference announcing the guilty plea on Tuesday.
Lafarge also faces charges of complicity in crimes against humanity in France over its activities in Syria, but the company denies the claims.
IANS