Charlotte "Charlie" Duncanis the second youngest of the Duncan family. She was originally the baby of the family, until it was announced in Good Luck Charlie, It's Christmas! that her mother Amy is pregnant again with a new baby. She was born three weeks before she was due. Teddy, her older sister, is making a video diary for Charlie to help her with their "special" family and some advice. She is currently 3 years old and in preschool. She spoke for the first time in Sleepless in Denver, but it seemed to have gone unnoticed by the family at that time. She is portrayed by Mia Talerico.
Charlie's favorite show is The Gurgles. In fact, Teddy bought her tickets to the Gurgles live just to get turned down. She also at one point had to watch the Gurgles to go to the bathroom. ("Charlie Is 2!", "Let's Potty")
Gabe and Charlie have a very interesting relationship. Initially, Gabe hated Charlie as she stole his spotlight as the youngest child. Slowly, he began to like her more especially after she threw up on Teddy! Gabe still thinks Charlie takes away the focus from him and 'ruined his life' as he tells Charlie about before Toby is born. Charlie seems OK with her brother, but she gets mad at him occasionally and sometimes tells on him like when she tells Bob Gabe stole his can in "Can You Keep a Secret?".
PJ sometimes uses Charlie to get girls. The affection PJ has for Charlie is obvious, as his reaction toward Charlie's secret playdate with a girl PJ was interested in was, "Aww, I can't stay mad at you." She replied, "I wuv PJ." It is obvious they have a loving brother-sister relationship. They hardly ever argue or fall out like the other Duncan siblings.
It is obvious that Teddy loves her little sister, Charlie. She makes video diaries for her to survive the Duncan family when she's not around in every episode. It is revealed she does this because she wants Charlie to be a 'good girl'.
Charlie's unexpected younger sibling. It was revealed that Amy was pregnant again and that Charlie would have a younger brother or sister in Good Luck Charlie, It's Christmas! the latest Christmas/Holiday Movie. It is inferred that Charlie may have a sense of jealousy towards the new baby, due to her no longer being the baby in the Duncan family. Later, she asks Teddy if Bob and Amy "take the baby back[from hospital]".
This was unjust, despite the fact Toby was born on her third birthday. Charlie said that she liked Toby as "her present.