This paper explores and explains key factors affecting the adoption of Artificial Intelligence (AI) in the auditing practice by a Big Four accounting firm, through the lens of the technology-organisation-environment (TOE) framework. Using the case study method, we conducted semi-structured interviews with decision-makers of the firm, complemented by secondary data. The data analysis identified significant anomalies to existing theories, revealing the specificity of adopting AI in audits. The findings showed that the firm’s adoption process was influenced by technology affordance, technology barriers, communication process, linking agents, firm scope and readiness, regulatory environment, predicted industrial changes and client’s acceptance. This study will contribute to the literature by providing a better understanding of AI adoption at the firm level, thus filling the gaps in the literature. It may strengthen the theories that underpin our understanding of the technology adoption by firms, revising, extending, and elaborating the TOE framework with more empirical evidence.