
He began performing as a voice actor in films in the 1930s. He was the voice of Cheetah in Tarzan films and produced the bird sounds in Disney's Snow White and the Seven Dwarfs (1937). Pullen's vocal contributions appear in many cartoons featuring Mickey Mouse, Betty Boop, and Popeye. Pullen was also the voice of the howling coyote in Cecil B. DeMille's "The Crusaders", and the squawks and jungle sounds for Martin Denny's "Quiet Village".
In 1945, Pullen began a collaboration with Spike Jones, providing sound effects and other comic gimmicks on many of the classic Jones recordings. Jones gave Pullen the stage name "Dr. Horatio Q. Birdbath."
Pullen was the voice of Pierre the Parrot in Walt Disney's Enchanted Tiki Room at Disneyland and Disneyworld. He was also heard in the San Francisco Bay Area as the voice of Roscoe the Dog on the Dr. Don Rose show on KFRC.
Pullen also appeared in nightclubs as a ventriloquist with a dummy named Johnny. Pullen was a longtime resident of Vacaville, California, where he performed puppet shows at the Nut Tree in the 1970s and 1980s and where he appeared with "Roscoe the Dog," a supposedly invisible dog puppeted by means of a stiffened dog leash.

Snow White and the Seven Dwarfs
1938 · as Birds (voice) (uncredited)

Who Killed Cock Robin?
1935 · as Cock Robin's Whistling (voice) (uncredited)

The Wise Little Hen
1934 · as Baby Chicks (voice) (uncredited)

Babes in the Woods
1932 · as Cat (voice) (uncredited)

The Flying Mouse
1934 · as Birds (voice) (uncredited)

The Goddess of Spring
1934 · as (voice) (uncredited)

Stolen Harmony
1935 · as Little Nell in Skit (uncredited)

The Golden Touch
1935 · as Bird (voice) (uncredited)

Big Man from the North
1931 · as Dogs (voice) (uncredited)

Figaro and Frankie
1947 · as Frankie (uncredited)

Mother Goose Melodies
1931 · as Whistling (voice) (uncredited)

Birds in the Spring
1933 · as Birds (voice) (uncredited)

Mickey Steps Out
1931 · as Cat (voice) (uncredited)

Holiday Land
1934 · as (voice) (uncredited)