<p>Walnut shell is widely generated agricultural waste which offers immense opportunities for high-value biovalorisation, transforming a significant environmental burden into a valuable resource. This sustainable approach converts walnut shell into various valuable products, fostering a circular bioeconomy through diverse pathways. This review explores various bioconversion strategies, viz., generation of bioenergy and biofuels through pyrolysis, biodiesel production and biogas generation. Additionally, it covers the chemical and material applications including activated carbon, biocomposites and natural dyes, replacing synthetic alternatives. This review covers pharmaceutical and cosmeceutical applications, food and feed uses, and agricultural and environmental solutions, highlighting their roles in promoting health, enhancing nutrition, and supporting sustainability. Economic and life cycle assessments are evaluated to ensure the viability and scalability of walnut shell biovalorisation. By leveraging technological advancements, life cycle assessments, and sustainability analyses, walnut shell biovalorisation ensures efficiency, environmental viability and economic benefits. This approach reduces waste disposal costs, creates new revenue streams, promotes rural development, enhances environmental sustainability and improves human health through value-added products, presenting a compelling solution for industry stakeholders and researchers.</p>