Contract farming is a vital organizational model for mitigating systemic risks in agricultural supply chains, yet it is persistently hindered by severe trust deficits and prohibitive legal enforcement costs. Traditional centralized credit evaluation systems often fail to encompass dispersed smallholder farmers, leaving their historical compliance locked as illiquid, implicit social capital. To address these structural vulnerabilities, this paper proposes a novel blockchain-enabled agricultural contract fulfillment mechanism grounded in decentralized identity (DID) and verifiable credentials. Rather than treating reputation as a direct transactional currency, we design a bidirectional anchoring architecture where on-chain reputation acts as a cryptographic trust anchor to validate the authenticity of verifiable credentials (VCs). These VCs transparently prove a farmer’s actual production capacity and off-chain agricultural records. Through the autonomous execution of smart contracts, this endogenous governance system links these authenticated capacity credentials directly to agricultural transactions. Successful fulfillment naturally yields a reputation premium, whereas opportunistic default, or the issuance of falsified credentials, triggers the immediate, systemic destruction of the responsible parties’credit capital. A multi-agent transaction simulation validates the proposed framework, demonstrating its efficacy in filtering market risks based on verifiable capacity and overcoming the cold-start dilemma for new rural entrants.