Alli Sims was born on July 15, 1981 and raised in Baton Rough, LA, Louisiana with her younger brother. Sims grew up singing in church and at various school functions. She began taking piano lessons at the early age of four. Sims sang the song "On My Own" from Les Miserables for the Junior Miss Georgia Pageant. She attended college in Mississippi and graduated in 2003. Sims is pursuing a career in pop music and plans to release some of her new recordings in the near future.

Sims is most known as Britney Spears' assistant and is rumored to be her cousin. She was in the news after being served deposition subpoena papers on August 12, 2007 requesting her to testify on behalf of Kevin Federline concerning Britney Spears' parenting capabilities. Spears and Federline are fighting for the custody of their two sons, Jayden James and Sean Preston Federline.