India Opal Buloni is a ten-year-old girl who recently relocated to an adult trailer park in Naomi, Florida. Having left her old friends behind and struggling with the absence of her mother, she experiences deep loneliness in her new environment. She views herself as a "Less Fortunate" and naturally gravitates toward others who seem isolated or abandoned.

Winn-Dixie is a large stray dog with patchy fur and a remarkably expressive face. He possesses a distinct ability to smile at humans when he wants to make friends or diffuse tension. Despite his rough exterior, he quickly becomes Opal's closest companion and serves as her primary bridge to meeting the other residents of Naomi.

Opal's father is a devoted clergyman who spends most of his time reading the Bible and drafting sermons. Operating as a single parent since his wife left the family years prior, he tends to retreat emotionally when discussing painful subjects. Opal compares this habit to a turtle pulling its head inside its shell.

Miss Franny Block is an elderly librarian whose father built her the town library when she was a young girl. She acts as a custodian of local history and enjoys sharing colorful stories from her past. Because she has outlived many of her peers, she relates to Opal's feelings of isolation.

Otis is a shy, quiet man who manages the local pet supply store where Opal seeks employment. He has a passion for music and secretly plays his guitar to soothe the caged animals. His past includes trouble with the law, which contributes to his cautious demeanor around others.

Amanda Wilkinson is a girl around Opal's age who frequents the local library to read advanced books. Opal initially perceives her as arrogant due to her pinched expression and abrupt conversational style. Beneath this abrasive exterior, she carries a heavy personal sorrow.

Gloria Dump is a kind, visually impaired older woman living on what local children consider a scary property. Rather than judging people by their outward appearance or past actions, she insists on seeing them with her heart. She maintains a sprawling garden where she helps Opal plant a "wait-and-see" tree.

Dunlap and Stevie Dewberry are brothers living in Naomi who frequently target Opal with teasing. Stevie tends to be the more aggressive of the pair, actively antagonizing Opal and spreading rumors about local residents. Dunlap displays a slightly softer edge, occasionally attempting to bridge the gap between them.

Littmus Block is Miss Franny Block's great-grandfather, a historical figure from the Civil War era. He returned from battle as a young orphan to find his home destroyed and his family gone. Seeking comfort after profound tragedy, he established a successful candy factory in Florida.

Sweetie Pie Thomas is a five-year-old girl who desperately wants a pet dog. She adores Winn-Dixie and regularly stops to admire him or invite him to events. She copes with her inability to own a real pet by collecting pictures of dogs.

Opal's mother left the family when Opal was three years old. She struggled with alcohol addiction and disliked the pressures associated with being a clergyman's wife. Though physically absent, her memory drives much of Opal's quest for connection.

Gertrude is a highly opinionated parrot living at Gertrude's Pets, named after the store's owner. She generally dislikes dogs but makes an exception for Winn-Dixie. She spends most of her time sitting on Otis's shoulder or observing the shop.

Carson Wilkinson is Amanda's five-year-old brother. His profound impact on his family explains much of his sister's difficult behavior and emotional state.