He has been the play-by-play radio announcer for the St. Louis Cardinals since 2006. He came to St. Louis after broadcasting games for the Chicago White Sox for eighteen years. His final broadcast for the White Sox was Game 4 of the 2005 World Series, which ended in the first World Series championship for the White Sox since 1917. The Cardinals won the World Series in 2006, and Rooney has the distinction of broadcasting for two different championship teams in consecutive years. In 2006, Rooney joined the Cardinals radio crew on KTRS, teaming with former player and veteran broadcaster Mike Shannon. Cardinal broadcasts returned to KMOX Radio in 2011, and Rooney has been there ever since.

Rooney was an announcer for the Minnesota Twins in the mid-1980s. In 1988, he joined the broadcasting team of the Chicago White Sox. He was a basketball announcer for the Chicago Bulls from 1989 to 1991. For many years, he was a broadcaster for Missouri Tigers basketball.

Rooney worked for CBS Radio from 1984 to 2003, nationally broadcasting various sports. He was an announcer for Major League Baseball, the National Football League, college football, and college basketball. He called Saturday baseball telecasts for Fox Sports from 1996 to 1998. In 2003 and 2004, he worked postseason Division Series games for ESPN Radio. He also announced NFL games on the Sports USA Radio Network.

Rooney was born in the Kansas City suburb of Richmond, Missouri. He began his broadcast career in the 1970s with assignments for various radio stations in Missouri and Oklahoma. In 1980, he began calling play-by-play for the Oklahoma City 89ers, a minor league baseball team. He was a broadcaster for the Louisville Redbirds beginning in 1983. 

In 2004, Rooney was inducted into the Missouri Sports Hall of Fame.