Harlan's broadcasting career began in 1982, when he became the TV and radio voice of the NBA's Kansas City Kings (now the Sacramento Kings). He then was a basketball announcer for his alma mater, the University of Kansas, for one year, then went on to call games for the NFL's Kansas City Chiefs from 1985-93. Harlan also split time with the University of Missouri (1986-89) calling football and basketball games, and worked as the play-by-play voice of the NBA's Minnesota Timberwolves for nine seasons. In 1994, he joined Fox Broadcasting Company as a NFL announcer, and in 1996, joined Turner Sports to cover NBA playoff games (he would begin calling games throughout the entire season in 1997, which he continues to do to this day).
In addition, Harlan has called Green Bay Packers preseason games; basketball games during the now-defunct Goodwill Games, which were owned by Time Warner; NFL games on NBC; college sports on ESPN; and several bowl games during college football season.
Known for his witty dialogue and vast assortment of creative banter, Harlan can be heard exclaiming: "Buckle up for..." (when any NBA Basketball player about to slam dunk the ball in the hoop) and "Right between the eyes!" and "He just sucked the gravity right out of the building!!" and "He's a flamethrower!!!" Harlan has also been known to say "With no regard for human life!" after an especially devastating play. The most well known was a dunk by Kobe Bryant on Latrell Sprewell. During his years in Kansas City with the Chiefs he was known to scream "Oh baby, what a play!" after a spectacular play by the Chiefs.