In this chapter, we address synthesis approaches for signal synchronization and secure communications of chaotic systems by using LMIbased fuzzy system design methods. Following a general form of TakagiSugeno fuzzy chaotic models, the structure of the response system is firstly proposed. Synthesizing from the observer and controller points of view, two developed drive-response systems achieve asymptotic synchronization. For chaotic communications, the asymptotical recovering of messages is ensured by the same framework. As a further application, a chaotic cryptosystem is proposed. The synchronization design is applied to transmit and decrypt the ciphertext. The combination of both chaotic signal and cyptosystem characteristics achieves communication with a higher level of security. Finally, several well-known chaotic systems are used in numerical simulations and DSP-based experiments.