This paper presents a novel physical layer secrecy enhancement technique for multicarrier communications based on dynamic filter hopping. Using the Filter Bank Multicarrier (FBMC) waveform, an efficient eavesdropping mitigation technique is developed using time- and frequency-varying prototype filters. Without knowledge of the filter assignment pattern, an eavesdropper will experience a high level of inter-carrier (ICI) and inter-symbol interference (ISI). With this severe receive signal-to-interference-plus-noise ratio (SINR) degradation for an illegitimate receiver, the secrecy capacity of the communication system is increased. At the same time, the interference at the legitimate receiver is designed to be negligible in comparison to the channel noise.