He was best known as one of the Mouseketeers on the Mickey Mouse Club, and as Robbie Douglas on the long-running ABC / CBS television series My Three Sons.

Character actor John Anderson is cast as Fisk Madden, who tries to drive Taggart off his land and gain Stella's favor.

Stella Faring reveals that she had been living in San Antonio, Texas, during the war, also the birthplace of Joan Crawford.

During production of My Three Sons, Grady appeared with his own band The Greefs on the series, writing two original songs for the show ("A Good Man to Have Around the House" and "Leaving It Up to You"), recorded a single with the Palace Guard ("Little People" b/w "Summertime Game") in 1966, and was the drummer for The Yellow Balloon, whose self-titled song became a minor hit in 1967.

The character of the original oldest brother, Mike (played by Tim Considine, who had earlier appeared with Grady in The New Adventures of Spin and Marty), was gradually eased out of the series, and a new youngest son, Ernie (Barry Livingston), was adopted into the family.

His works included music for the Blake Edwards comedy film Switch, the theme song for The Phil Donahue Show[7] and for EFX, a Las Vegas multimedia stage show starring Michael Crawford, David Cassidy, Tommy Tune, and Rick Springfield.

In fall 2008, Grady released Boomer: JazRokPop, a collection of songs written for and about the baby boom generation.

Grady's parents were divorced when he started My Three Sons and he stated later that Fred MacMurray and show producers Don Fedderson and Ed Hartman were the "father figures I needed.