Windhorst attended high school in Akron, Ohio at St. Vincent - St. Mary High School, the same school that James would later attend, and graduated from Kent State University with a degree in journalism in 2000. Windhorst began covering James during his high school playing career, and began covering the Cavaliers in 2003, the year that James was drafted. While James was the youngest player in the NBA, Windhorst was the youngest traveling NBA beat writer. In 2007 he co-wrote The Franchise: LeBron James and the Remaking of the Cleveland Cavaliers with renowned sports columnist Terry Pluto. His writing at The Plain Dealer was honored by the United States Basketball Writers Association for Best Game Story in 2009, and by the Associated Press.
In 2010, Windhorst left the Plain Dealer for ESPN to cover James' new team, the Miami Heat. Prior to leaving The Plain Dealer, he contributed columns to ESPN.com and made appearances on ESPN First Take. In an interview, Windhorst stated that "obviously LeBron's a huge factor" in his decision to join ESPN, but that the Cavaliers "need to move on" without James.
On October 10, 2014, it was announced that Windhorst would join ESPN Cleveland on WKNR AM 850 in Cleveland to be their Cavaliers beat reporter and analyst, as well as host his own weekly program on sister station WWGK AM 1540. The move followed James' re-signing with the Cavaliers in 2014.