John Thorn has served as the long-time editor and author of Total Baseball (with Pete Palmer, Mike Gershman, and David Pietrusza) and many other outstanding baseball books including: The Hidden Game of Baseball (with Pete Palmer, 1984), The Complete Armchair Book of Baseball (2004), Treasures from the Baseball Hall of Fame: The Official Companion to the Collection at Cooperstown, The Whole Baseball Catalogue (with Bob Carroll), A Century of Baseball Lore, Baseball's 10 Greatest Games, and The Relief Pitcher.
He was profiled in the book Baseball: The Writers' Game by Mike Shannon.
In the book, Baseball in the Garden of Eden, published by Simon and Schuster in March 2011, Thorn addresses the issue of the origins of baseball and dispels some of the myths about the role of Alexander Cartwright in laying down the rules of the modern game.
Thorn writes two columns for the Woodstock Times: "Play's the Thing" (largely sports) and "Wake the Echoes" (arts and letters). He is also a columnist for Voices, the publication of the New York Folkore Society.
In June 2006, SABR awarded Thorn its highest award, the Bob Davids Award. The award honors those whose contributions to SABR and baseball reflect the ingenuity, integrity, and self-sacrifice of the founder and past president of SABR, L. Robert "Bob" Davids. On March 1, 2011, he was appointed as Major League Baseball's official historian, replacing the late Jerome Holtzman, who held the position from 1999 until his passing in 2008.
On March 15, 2011, Commissioner Bud Selig appointed him to head a new 12-person Baseball Origins Committee created to study the origins of baseball. In 2013, he was honored by SABR with the Henry Chadwick Award.