Eig was born in Brooklyn, New York and grew up in Monsey, New York. His father was an accountant and his mother was a stay-at-home mom and community activist. Eig began working for his hometown newspaper when he was 16. He attended Northwestern University's Medill School of Journalism, graduating in 1986 with a bachelor’s degree. After college he worked as a news reporter for the New Orleans Times-Picayune, The Dallas Morning News, Chicago magazine, and The Wall Street Journal. Eig has taught writing at Columbia College Chicago and lectures at Northwestern. He has written as a freelancer for many outlets, including The New York Times, Washington Post, and online edition of The New Yorker. He is married to Jennifer Tescher and has three children. He lives in Chicago.
Eig appeared on The Daily Show with Jon Stewart in May 2010. He has appeared in two PBS documentaries—Prohibition and Jackie Robinson—made by Ken Burns and Florentine Films. He is currently working with Burns as a consulting producer on a documentary about Muhammad Ali.
Eig's first book was Luckiest Man: The Life and Death of Lou Gehrig (2005). Opening Day: The Story of Jackie Robinson's First Season was his second book. For his third book, Get Capone, Eig discovered thousands of pages of never-before-reported government documents on the government's case against Capone. The Birth of the Pill (2014), Eig's fourth book, told the story of the renegades who invented the first oral contraceptive.
In a 2017 review of Ali: A Life, Joyce Carol Oates, writing for The New York Times, said: "This richly researched, sympathetic yet unsparing portrait of a controversial figure for whom the personal and the political dramatically fused could not come at a more appropriate time in our beleaguered American history…. As Muhammad Ali’s life was an epic of a life so “Ali: A Life” is an epic of a biography. Much in its pages will be familiar to those with some knowledge of boxing but even the familiar may be glimpsed from a new perspective in Eig’s fluent prose; for pages in succession its narrative reads like a novel — a suspenseful novel with a cast of vivid characters who prevail through decades and who help to define the singular individual who was both a brilliantly innovative, incomparably charismatic heavyweight boxer and a public figure whose iconic significance shifted radically through the decades as in an unlikely fairy tale in which the most despised athlete in American history becomes, by the 21st century, the most beloved athlete in American history.”
- Luckiest Man: The Life and Death of Lou Gehrig (2005)
- Opening Day: The Story of Jackie Robinson’s First Season (2007)
- Get Capone: The Secret Plot that Captured America's Most Wanted Gangster (2010)
- The Birth of the Pill: How Four Crusaders Reinvented Sex and Launched a Revolution (2014)
- Ali: A Life (2017)
- 2005 Casey Award for best baseball book of the year, Luckiest Man
- 2014 Washington Post "Best Books of the Year" for The Birth of the Pill
- 2015 Society of Midland Authors, non-fiction book of the year, The Birth of the Pill
- 2017 NAACP Image Awards, finalist, Ali: A Life
- 2017 William Hill Sports Book of the Year, best sports book, finalist, Ali: A Life
- 2018 Plutarch Award, best biography, finalist, Ali: A Life
- 2018 PEN/ESPN Award for Literary Sports Writing, Literary Sports Writing, winner for Ali: A Life
- 2018 The Times Biography of the Year, Sports Book Awards, London, for Ali: A Life
- 2018 Sports Book of the Year, Sports Book Awards, for Ali: A Life
- "A new biography of Muhammad Ali". The Economist. 26 October 2017.
- "Al Capone Wasn't Brought Down By Eliot Ness, It Was The IRS: Author Jonathan Eig On Jon Stewart (VIDEO)". Huffington Post. 2010-07-04. Retrieved 2017-12-08.
- Kogan, Rick. "Jonathan Eig's 'Ali' book may become a documentary by Ken Burns". chicagotribune.com. Retrieved 2017-12-08.
- Oates, Joyce Carol (2017-11-28). "Muhammad Ali, Beginning to End for the First Time in a Book". The New York Times. ISSN 0362-4331. Retrieved 2017-12-08.
- "CASEY Award". Spitball: The Literary Baseball Magazine.
- "How women gained control of pregnancy". Washington Post. Retrieved 2017-12-08.
- "NAACP | Nominees Announced for 49th NAACP Image Awards". NAACP. 2017-11-20. Retrieved 2017-12-08.
- "2017 William Hill Shortlist Announced". Foyles. Retrieved 2017-12-08.
- John Maher (February 21, 2018). "Long Soldier, Zhang, Le Guin Win At 2018 PEN Literary Awards". Publishers Weekly. Retrieved February 21, 2018.
- "The 2018 PEN America Literary Awards Winners". PEN America. February 20, 2018. Retrieved February 21, 2018.
- Porter Anderson (January 31, 2018). "Industry Notes: PEN America's Finalists". Publishing Perspectives. Retrieved February 21, 2018.