In this study, the authors propose a new group testing based (GTB) error control codes (ECCs) approach for improving the reliability of memory structures in computing systems. Compared with conventional single‐ and double‐bit error correcting codes, the GTB codes provide higher reliability at the multi‐byte error correction granularity. The proposed codes are cost‐efficient in their encoding and decoding procedures. Instead of requiring multiplication or inversion over Galois finite field like most multi‐byte ECC schemes, the proposed technique only involves bitwise XOR operations, therefore, significantly reducing the computation complexity and latency. For instance, to correct m errors in a Q‐ary codeword of length N, where , the compute complexity is mere . The GTB codes trade redundancy for encoding and decoding simplicity, and are able to achieve better code rate than other ECCs of the same trade‐off. The proposed GTB codes lend themselves well to designs with high reliability and low computation complexity requirements, such as storage systems with strong fault tolerance, or compute systems with straggler tolerance, and so on.