This study investigates whether audit clients’ blockchain activities (including crypto-related activities) affect audit risk by examining the association between blockchain disclosures in 10-K filings and audit fees. Focusing on U.S. firms between 2013 and 2020, we empirically show that audit fees are higher for companies disclosing blockchain activities in 10-K filings. We further find that this positive association is more pronounced for companies disclosing current blockchain implementation than for companies with plans for blockchain activities. The results indicate that clients’ blockchain activities influence audit risk as assessed by external auditors. As blockchain technology and its applications are emerging, our findings have implications that should be considered by auditors, regulators, and top management.