The actresses lent their voices to the English-language version of the Japanese blockbuster from Oscar-winning filmmaker Hayao Miyazaki.
Miyazaki, who rarely makes appearances in the United States, also attended the premiere at Manhattan's Museum of Modern Art.
Based on the novel by Diana Wynne Jones, "Howl's Moving Castle" tells the tale of a teenage girl, voiced by Mortimer, turned into a 90-year-old woman (Simmons) by an evil witch (Bacall) after she catches the eye of a mysterious wizard (Christian Bale,) who just happens to be the man the witch loves.
As the girl tries to break the spell, she discovers the handsome wizard, who travels the world in an extraordinary moving castle, is also the victim of a cruel enchantment. Together, with the help of a magical fireball voiced by Billy Crystal, the pair works to restore each other to their true natures.
"Howl's Moving Castle" will open in select theaters Friday.