In 1991, Farmer took a part-time role on White Sox radio broadcasts, then was a full-time color commentator from 1992 to 2005. He became well known among fans by the nickname "Farmio". In 2006, he took over play-by-play from John Rooney, and served in that role through the 2019 season, with broadcast partners Chris Singleton (2006–2007), Steve Stone (2008), and Darrin Jackson (2009–2019). Farmer served a total of 29 seasons as a White Sox broadcaster; 28 of them full-time, and 14 giving play-by-play.