Leahy was born in Newark, New Jersey. At age 10, he moved with his family to a suburb of Los Angeles, California. He is a graduate of Yale University.

A highly regarded feature writer known for his intimate portraits of subjects, Leahy explores everything from social issues to sports. He has written for the Los Angeles Times, Arkansas Democrat-Gazette, and his work has appeared in Playboy Magazine and Sports Illustrated.

Leahy has published two non-fiction books: Hard Lessons (1988) and When Nothing Else Matters (2004), which was heralded by GQ Magazine as "the best sports book of the year."

Along the way, he has written about subjects as wide-ranging as presidential politics, rural poverty, obesity in the American South, malaria in sub-Saharan Africa, the housecleaner dubbed fisherman-savior of Elian Gonzalez, the Army’s recruiting efforts amid the specter of the Iraq war, corporate scandals, a nudist camp, his mother’s struggles with Alzheimer’s, and the playing comeback of basketball legend Michael Jordan in Washington.

• His story on the life of a paroled child murderer spared execution in the early '70s because of a Supreme Court decision that briefly rendered the death penalty unconstitutional won the Washington D.C. Society of Professional Journalists’ best feature story award.

• In 2006, his Washington Post Magazine story about a single mother from Massachusetts who took her two young children across the country to meet their father — a sperm donor known to the woman for years only as Donor 929 — won honors from the Society of Professional Journalists as the best magazine story in the country for that year.

• His sports work has been selected four times for The Best American Sports Writing anthologies, published by Houghton Mifflin Company, which annually features the 25 best sports stories in the nation.

In his review of When Nothing Else Matters, English journalist Simon Barnes of The Times wrote "A better book, a perceptive writer, might have noticed that there was something heroic in all this: but Leahy is too deeply committed to his premise that everything Jordan does is, by definition, shameful."

Leahy resides with his wife and son in a suburb of Washington D.C.

• Leahy, Michael. (1988a) Hard Lessons, Boston. Little, Brown and Company.
• Leahy, Michael. (2004a) When Nothing Else Matters, New York. Simon & Schuster.

Cramer, Richard (editor). (2004a) The Best American Sports Writing, New York. Houghton Mifflin Company.