Atopic dermatitis (AD) is a chronic, inflammatory skin disease that can significantly affect quality of life. Presence, severity, and therapeutic response of AD are traditionally reported through clinical assessments including the Eczema Area and Severity Index or Investigator's Global Assessment. These clinical rating scales are visual assessments used in clinical trials to denotate AD severity. Alternatively, biomarkers open the potential to further enhance diagnosis of AD, assess disease status and severity, and potentially enable tailored treatment options for patients. Biomarkers can be classified according to their clinical use, clinical presentation, and underlying/endogenous molecular mechanisms. Specifically, interleukin (IL)-13, which has been shown to be a key biomarker in AD pathogenesis, can be used for prediction of AD development and to monitor clinical severity/response to treatment. Treatment with tralokinumab, a human monoclonal antibody that binds directly to-and subsequently blocks signaling of-IL-13, has been shown to reduce inflammation, re-balance the skin microbiome, and improve the skin barrier in patients with AD. In this review, key AD-related biomarkers, the role of IL-13 in driving AD pathogenesis, and the impact of IL-13 inhibition by tralokinumab on other AD-related biomarkers are discussed.