Allison Smith's career started on Broadway at the age of nine, in the original production of "Evita", quickly followed by her landing the title role of "Annie" on Broadway in the musical "Annie" at the age of ten. She was the longest-running and youngest star of a Broadway musical at that time, playing the role for over 1,000 performances; nearly 3 years.

She's given vocal performances at Carnegie Hall, The Kennedy Center, Radio City Music Hall, and The White House. After "Annie", she was cast on "Kate and Allie", playing the role of "Jennie Lowell" on CBS for six seasons. Allison recurred in all seven seasons of NBC's The West Wing (1999) as "Mallory O'Brien", the chief of staff's daughter / Sam Seaborn's (Rob Lowe's) love interest.