In this study, we propose a novel coding method, called geometry permutation decoding (GPD), for square sensor topologies. The GPD algorithm provides a two-dimensional geometry construction and decodes information sequences based on this construction. The two-dimensional construction for square wireless sensor networks (WSNs) is suitable for employing channel coding, especially product codes and finite geometry codes, and for detecting multiple error patterns. A majority logic decoding (MLD) is a less correcting efficient but simpler-to-implement decoding method. To improve the drawback of the less correcting capacity, the GPD algorithm not only gives better bit error rates at low decoding complexity but also provides a new solution suitable for decoding in two-dimensional WSNs. In particular, this decoding work in the two-dimensional WSNs is achieved over the bit level without a packet level so that the overhead in the network layer can be reduced.