Abstract Modern operating systems have adopted Berkeley Packet Filters (BPF) as a mechanism to extend kernel functionalities dynamically, e.g., Linux’s eBPF or RIOT’s rBPF. The just-in-time (JIT) compilation of eBPF introduced in Linux eBPF for performance has however led to numerous critical issues. Instead, RIOT’s rBPF uses a slower but memory-isolating interpreter (a virtual machine) which implements a defensive semantics of BPF; and therefore trades performance for security. To increase performance without sacrificing security, this paper presents a fully verified JIT implementation for RIOT’s rBPF, consisting of: i/ an end-to-end refinement workflow to both proving the JIT correct from an abstract specification and by deriving a verified concrete C implementation; ii/ a symbolic CompCert interpreter for executing binary code; iii/ a verified JIT compiler for rBPF; iv/ a verified hybrid rBPF virtual machine. Our core contribution is, to the best of our knowledge, the first and fully verified rBPF JIT compiler with correctness guarantees from high-level specification to low-level implementation. Benchmarks on microcontrollers hosting the RIOT operating system demonstrate significant performance improvements over the existing implementations of rBPF, even in worst-case application scenarios.