Josephine March, known as Jo, stands tall and thin at fifteen, her long limbs and sharp grey eyes contrasting her long brown hair, called her "one beauty." Bold and outspoken, she disdains conventional femininity, preferring running, climbing trees, and staging plays. Her fierce temper, a "fatal flaw," is gradually tempered by maturity and her mother's guidance.

She channels restless energy into writing, retreating to the attic in her "scribbling suit" – a black pinafore and cap – finding empowerment and escape in creating stories. Financial hardship strikes her family after their Gettysburg home is destroyed during Confederate occupation, forcing them to relocate to Newcord to live with estranged great-aunt Aunt March. To support them, Jo becomes Aunt March's companion and pursues professional writing. Facing harsh criticism and rejection from newspaper reporter Anthony Boone, she perseveres, eventually earning his respect and forging a professional friendship.

Jo shares a deep bond with her sisters, especially the gentle, frail Beth. Beth's scarlet fever and eventual death awaken unprecedented tenderness in Jo, who becomes her devoted caretaker, learning the value of domestic duties and familial love. Her spirited friendship with neighbor Theodore "Laurie" Laurence, filled with mischief, leads to his marriage proposal, which she rejects, seeing him only as a brother.

Seeking new experiences, Jo moves to New York as a governess. There, she meets German professor Friedrich Bhaer, her mentor and critic. He challenges her sensationalist writing, advocating purposeful literature. Though initially resistant, she values his intellectual companionship. After Beth's death, Professor Bhaer visits the March family and proposes; Jo accepts and they marry.

Using an inheritance from Aunt March, Jo and Bhaer establish Plumfield, a school for boys, blending her domestic life with professional fulfillment as she works alongside her husband. In later years, depicted in *Little Women II: Jo's Boys*, she expands the school to include girls and raises her own two sons, maintaining her spirited nature while embracing her role as educator and matriarch.

Throughout her development, Jo evolves from a rebellious tomboy resisting gender norms into a woman who reconciles her independent spirit with societal expectations, retaining her determination and outspokenness while finding purpose in nurturing others through family and school.