<p>Frequent fraudulent practices expose a lack of transparency in supply chains, prompting firms to address the challenge of improving supply chain transparency (SCT). As suppliers are the cornerstone of supply chain activities, this research explores how SCT can be enhanced from the perspective of suppliers. A sustainable multi-criteria hybrid approach is developed that facilitates the quantitative assessment of suppliers and improves SCT. The proposed framework integrates interval-valued neutrosophic sets (IVNS) with AHP and the Entropy Weight Method (EWM) to address the uncertainty and inconsistency of real-world information. A new weight calculation formula, a novel scoring function, and weighted average (WA) operator further refine the assessment process. This research contributes by introducing a transparency-driven supplier evaluation model that systematically quantifies the impact of suppliers on SCT while addressing uncertainty and inconsistency in decision-making. Results from methods comparisons and sensitivity analyses indicate that the proposed approach outperforms previous models in terms of both effectiveness and practicality. The findings indicate that this framework improves the reliability of supplier assessments and provides several practical recommendations.</p>