As quantum computing advances, the conventional foundations of information security, rooted in asymmetric cryptography and classical hash functions, face unprecedented vulnerabilities. This poses a critical challenge for Islamic banking, which is predicated on the authenticity, transparency, and Shariah compliance of financial contracts. While contemporary technological solutions frequently rely on blockchain infrastructures, both jurisprudential analysis and empirical evidence indicate that blockchain is not fully congruent with key principles of Islamic law, including the prohibition of gharar (excessive uncertainty) and the clear delineation of ownership. This paper proposes a blockchain-averse framework designed to strengthen the digital security of non-interest-based contracts by leveraging quantum key distribution and post-quantum-resistant cryptographic algorithms. Within this framework, three foundational Shariah principles—verification of contract authenticity, prevention of tampering and forgery, and assurance of ownership transparency—are embedded in a multilayered cryptographic architecture. After examining the doctrinal underpinnings of Islamic commercial law and anticipating future security requirements, the paper outlines the proposed model and assesses its feasibility within the Islamic banking system of Iran and those of other Muslim-majority jurisdictions. The findings demonstrate that it is possible to deliver a secure, ethically grounded, and scientifically robust framework for safeguarding Islamic contracts against quantum-era threats, thereby transcending blockchain’s limitations and preserving both public trust and Shariah integrity in the digital environment.