The proliferation of Internet of Things (IoT) devices across critical infrastructure in the United States has created unprecedented security challenges, particularly concerning firmware integrity throughout complex supply chains. This paper presents a novel framework for supply chain integrity verification utilizing distributed ledger technology to establish cryptographic attestation mechanisms for IoT firmware updates. Our research addresses the growing concern over supply chain attacks, exemplified by incidents such as the SolarWinds breach, which demonstrated the catastrophic potential of compromised software distribution channels. The proposed framework leverages blockchain-based attestation to create immutable records of firmware provenance, enabling real-time verification of update integrity from manufacturer to end-device deployment. Through comprehensive analysis of 847 IoT devices across six major manufacturers in the U.S. market, we demonstrate significant improvements in security posture while maintaining acceptable performance overhead. Results indicate a 94.7% reduction in successful supply chain compromise attempts and a 12.3% improvement in update verification time compared to traditional certificate-based approaches.