In 1997, Egan made her first appearance in a Disney film as the feisty Megara from Disney's Hercules. This brought her critical acclaim and recognition for her voice acting skills. She later reprised her role for Megara in the episode "Hercules and the Aetolian Amphora" from the television series, House of Mouse, and the video game Kingdom Hearts II.
She also voiced Madame Gina in Porco Rosso and Lin in Spirited Away.
Apart from acting, Egan has a frequent career in music. She recorded "I Won't Say (I'm in Love)" during her role as Megara for the Hercules soundtrack, and gargned critcal acclaim for her singing for her role as Belle on Broadway.
Later, she provided the singing voice of Angel in Lady and the Tramp II: Scamp's Adventure, in which she recorded "Always There" alongside Roger Bart, Jeff Bennett, and returning Disney icon Jodi Benson.