After he had acquired his avian—and other—powers, he was recruited by a top-secret government agency, Inter-Nation Security, and now works full-time fighting crime, assisted by his pet eagle, who responds to the name of "Avenger".

In the show, Harvey is a defense attorney, and his clients are generally classic Hanna-Barbera characters given new roles (Fred Flintstone appears, for example, as a mafia don, and Boo-Boo Bear is accused in one episode of being a mad bomber).

Instead of being a clever superhero, this version of Birdman is portrayed as a semi-competent, bungling lawyer, although among the show's increasingly outlandish cast of characters, he is often the straight man.

In the series finale, "The Death of Harvey Birdman", he returns to his superheroing ways, defeating an old enemy before being suddenly hit with a bus and killed.

Harvey Birdman, along with Space Ghost, appeared in the background in multiple scenes of the Season 4 episode of The Powerpuff Girls titled "Members Only".