Carreyrou graduated from Duke University in 1994 with a B.A. in political science and government.
After graduation, he joined the Dow Jones Newswires. In 1999 he joined The Wall Street Journal Europe at Brussels. In 2001 he moved to Paris to cover French business and other topics such as terrorism. In 2003 he was appointed the deputy bureau chief for Southern Europe. He covered French politics and business, Spain and Portugal. By 2008 he was the deputy bureau chief and later bureau chief of the health and science bureau in New York.
In late 2015 Carreyrou began a series of investigative articles on Theranos, the blood-testing start-up founded by Elizabeth Holmes, that questioned its claim to be able to run a wide range of lab tests from a tiny sample of blood from a finger prick.
In 2003, Carreyrou shared the Pulitzer Prize in Explanatory Reporting with a team of Wall Street Journal reporters for a series of stories that exposed corporate scandals in America. Carreyrou co-authored the article Damage Control: How Messier Kept Cash Crisis at Vivendi Hidden for Months, published Oct. 31, 2002.
In 2003, Carreyrou won the German Marshall Fund's Peter R. Weitz Junior Prize for excellence in reporting on European affairs for his detailed coverage of the downfall of Vivendi Universal SA and its chairman, Jean-Marie Messier.
In 2004, Carreyrou shared the German Marshall Fund's Peter R. Weitz Senior Prize for excellence in reporting on European affairs with a team of six The Wall Street Journal journalists. In the five-part series titled The Disintegration of the Trans-Atlantic Relationship over the Iraq War Carreyrou contributed the article In Normandy, U.S.-France Feud Cuts Deep. Published on February 24, 2003, while Carreyrou was based in Paris, the article explored how France's Normandy region, site of the D-Day landings, was caught between gratitude for the U.S. role in World War II and France's opposition to war in Iraq.
In 2015, Carreyrou shared the Pulitzer Prize for Investigative Reporting with a team of investigative reporters at The Wall Street Journal for "Medicare Unmasked," a project that forced the American government in 2014 to release important Medicare data kept secret for decades, and in a sweeping investigative series uncovered abuses that cost taxpayers billions. Carreyrou co-authored four articles in the series: Taxpayers face big tab for unusual doctor billings, A fast-growing medical lab tests anti-kickback law, Doctor ‘self-referral’ thrives on legal loophole and Sprawling medicare struggles to fight fraud.