This work presents an improved SHA-256 hashing algorithm that incorporates a novel bent-function-based S-Box to boost security while maintaining computational efficiency. The suggested method decreases the rounds from 64 to 32 while preserving strong cryptographic characteristics. The novel S-Box attains significant nonlinearity (NL = 112), robust avalanche properties (DSAC = 316), and an iteration period of 256, hence providing resilience against algebraic and linear assaults. Experimental assessments—comprising SAC, BIC, and collision analysis—exhibit enhanced diffusion, uniform hash distribution, and significant sensitivity to input modifications, with collision occurrences restricted to three. The findings confirm that the suggested framework provides enhanced security metrics and operational efficiency, rendering it appropriate for high-performance applications like blockchain and smart contracts.