The diplomatic environment has an important impact on the overseas development of companies. Based on the number of remarks made by the Ministry of Foreign Affairs of the People’s Republic of China from 2009 to 2022, this paper constructs an indicator capturing companies’ exposure to the risk of the diplomatic environment. This paper empirically tests the impact of diplomatic environmental risk on audit fees of international companies. The results show that the more companies are exposed to the diplomatic environment risk, the higher audit fees are. After distinguishing auditors’ heterogeneity, we find that the risk of the diplomatic environment significantly increases audit fees of non-“Big Four” accounting firms. Mechanism analysis reveals that both agency costs and audit inputs play intermediary roles between diplomatic environmental risk and audit fees. Results of this paper show the impact of macro-environmental risk on audit decisions, and enrich the research on the factors affecting audit fees of companies.