This paper focuses on the security aspects of the Three-level Mobility Model (TLMM) in the next-generation networks. Prior research has indicated that hierarchical architectures outperform other network topologies in terms of handoff delay, location update, and signaling overhead in mobile networks. The optimality test of the time-bandwidth product proved the supremacy of the three-tiered architecture of mobile networks in literature. However, earlier works of TLMM have not addressed the security issues. Designing a security protocol for TLMM is therefore the goal of this research. Our solution to the current research gap is a lightweight blockchain-based security protocol that can be used for local, regional, and global mobility. The work’s uniqueness resides in its proposal of a protocol to establish a peer-to-peer network where users can communicate with the data stored in a secure distributed ledger, reducing the amount of duplicate information that users must transfer. The implementation of blockchain technology is done using Hyperledger Composer and Hyperledger Fabric. Burrows-Abadi–Needham (BAN) logic has been used in the formal security verification of the suggested system to provide mutual authentication among the participants. Furthermore, the suggested model performs noticeably better than the other current systems by providing thirteen distinct security characteristics, requiring less processing time (about 8 ms) and communication overhead (around 2832 bits).