"Violet Evergarden" is set in a post-war world, where the titular character, Violet Evergarden, is a former soldier adjusting to civilian life. The story begins after a devastating war between the nations of Leidenschaftlich and Garderik, which has left Violet emotionally scarred and physically disabled, having lost both her arms, which are replaced with mechanical prosthetics. Violet was raised as a weapon, trained solely for combat, and her only connection to humanity was through her commanding officer, Major Gilbert Bougainvillea, who treated her with kindness and taught her to read and write. After the war, Gilbert is presumed dead, leaving Violet adrift and struggling to understand human emotions.

To find purpose and meaning in her life, Violet becomes an Auto Memory Doll, a profession where individuals transcribe people's thoughts and feelings into letters. Through this work, Violet travels across the continent, meeting various clients and helping them articulate their emotions. Each assignment brings her closer to understanding the complexities of human relationships and the nuances of love, grief, and longing. Her journey is both external, as she interacts with diverse individuals, and internal, as she grapples with her own unresolved feelings for Gilbert and her past as a soldier.

The narrative is episodic, with each episode or arc focusing on a different client and their story. These vignettes explore themes such as familial love, unspoken regrets, and the power of communication. Violet's interactions with her clients often mirror her own emotional struggles, allowing her to grow and develop a deeper understanding of herself and the world around her. Key supporting characters include Claudia Hodgins, the president of the CH Postal Company, who becomes a paternal figure to Violet, and Benedict Blue, a fellow employee who provides comic relief and camaraderie.

As the series progresses, Violet's quest to comprehend Gilbert's final words to her—"I love you"—becomes a central focus. Her journey is marked by moments of profound emotional revelation, culminating in a deeper understanding of love and loss. The series balances its episodic structure with an overarching narrative that ties Violet's personal growth to her evolving relationships with those around her. The story concludes with Violet achieving a sense of closure and acceptance, having come to terms with her past and found a place in the world beyond the battlefield.