Growing integrity concerns have undermined confidence in carbon offset markets. Despite extensive discussion of quality issues, a systematic understanding of how different institutional architectures shape integrity mechanisms remains critically limited. In this study, we comparatively analyze two major compliance-linked offset systems: China’s new Certified Emissions Reduction scheme and California’s reauthorized Compliance Offset Program. We reveal how their unique architectures—China’s centralized, state-led model with supplier liability versus California’s decentralized, public–private framework with buyer liability—shape mechanisms that maintain high integrity. While both systems share core principles and are converging toward standardized approaches to enhance operational feasibility, their implementation reveals different strategies for balancing rigor with administrative efficiency. This is evident in their additionality assessments—both tend to employ protocol-level approaches yet differ in protocol design and project review requirements—and extends to strategies for permanence, leakage, and co-benefits. Both systems face persistent challenges, but are turning to technological solutions, such as big data and remote sensing, to enhance monitoring and verification. Ultimately, no single model is superior, and effective design is context-dependent. The lessons from these jurisdictions provide critical evidence for policymakers on strengthening offset integrity and future international carbon markets.