This document proposes a new scalable key management scheme for wireless sensor networks (WSNs) using unital design theory. Existing key pre-distribution schemes suffer from low scalability or degraded performance metrics like storage overhead and resiliency for large networks. The proposed scheme aims to enhance scalability without degrading other metrics. It introduces a naive mapping from unital design to key pre-distribution showing high scalability. It also proposes an enhanced unital-based scheme maintaining good key sharing probability while further improving scalability. Analysis shows the approach outperforms existing schemes in criteria like storage overhead, scalability, and resiliency.