SummaryInternet of Things (IoT) networks continue to be deployed and play a crucial role in our daily life. Thus, ensuring their security is of utmost importance. This necessitates the use of cryptographic materials to maintain the confidentiality of exchanged data between IoT devices (or sensor nodes). The key component of these cryptographic materials is the encryption and decryption keys. In resource‐constrained networks like sensor and IoT networks, employing symmetric pairwise keys offers a trade‐off between resource saving and security. However, symmetric cryptosystems suffer from node compromising attacks. In addition, such networks often require the post‐deployment of new IoT devices either periodically or based on specific use cases leading to a multi‐phase IoT networks. So, key establishment is required to secure newly added node communications. This paper presents an adaPtive and rObust Key pre‐distribution (POK) that enables key establishment between deployed nodes. POK enhances the generation and pre‐loading of keys in sensor nodes. The fundamental concept of POK involves pre‐loading newly added IoT or sensor nodes with pairwise keys computed using a hash function and taking into account the expected number of future post‐deployments. Through a comparative analysis with related works, POK minimizes communication overhead, eliminates the need for time synchronization, and offers an energy‐efficient scheme. Furthermore, POK offers a resilience to node compromising attack by the self‐healing property, where compromised nodes have a limited effect on the network, and newly deployed nodes remain unaffected.