In 1989, Benson (working as a Broadway star at the time) made her theatrical debut as Ariel in The Little Mermaid. The filmmakers felt that it was necessary to have both Ariel's speaking and singing voices played by the same person, and therefore considered her a perfect candidate. She also briefly voiced Vanessa (Ursula's alter ego) on behalf of Pat Carroll.
Benson's vocal talents were given critical acclaim from a wide variety of film critics. It was for this film that she recorded her signature song "Part of Your World", which audiences around the world have grown to know and love.
The success of The Little Mermaid spawned an animated TV series in the mid-90s, followed by two direct-to-video sequels (the first in 2000 and the second in 2008). Benson has continued to reprise her role as Ariel in most Disney-related media, including the animated television series House of Mouse (in which she also voiced Belle from Beauty and the Beast on behalf of Paige O'Hara).
Benson is also famous for voicing several other Disney characters from various films and television series, including Weebo in Flubber, Barbie in Toy Story 2 and 3 as well as Hawaiian Vacation, Helen of Troy in the Hercules TV series and Zero to Hero, Lady in Lady and the Tramp II: Scamp's Adventure, and Anita in 101 Dalmatians II: Patch's London Adventure. In 2007, Benson even landed a supporting role as Sam in Enchanted, which remains one of Benson's few live-action film roles to-date and her only Disney-related one.
In addition to reprising her role as Ariel in the Sofia the First special "The Floating Palace", Benson also voiced Queen Emmaline. She also voices a character in Tales from the Resistance: Back to the 2nd Dimension.