Kim Atienza began his career in broadcasting as a voice talent, providing Filipino dubs for Japanese anime and tokusatsu series in the 1980s and 1990s. This work started after he was encouraged to audition for voice commercials, leading to opportunities in dubbing. His early roles included voicing Takeru, the leader character also known as Michael Joe, in the Tagalog dub of the Super Sentai series Hikari Sentai Maskman. He also provided voices for other series in this genre, such as Ultraman Ace and Fireman.

In 1999, Atienza took on the role of Kenichi Go, the protagonist of the robot anime Voltes V, for a film version released in the Philippines that year. In this English-language Philippine dub, the character was renamed Steve Armstrong. His voice acting work during this period also included the role of Kazuya Ryuzaki, renamed Richard Hartford, in the anime Daimos.

His career as a voice actor is considered an early phase of his long and prominent career in Philippine media, which later shifted to on-camera hosting, weather forecasting, and presenting educational content.