The first Disney princess is Snow White. She is the main character from Disney's first animated feature film, "Snow White and the Seven Dwarfs," which premiered in 1937. Snow White is recognized as the first Disney Princess and set the standard for subsequent Disney heroines.
Interestingly, there was a character named Persephone in a 1937 Silly Symphonies short who could be considered a princess, but Snow White holds the title as the first official Disney princess in the full-length animated film franchise.