This paper presents a novel approach to secure communication using Fractional-Order Chaotic Systems (FOCS) and a Step-By-Step Sliding-Mode Observer (SBS-SMO). The study aims to enhance the security of encrypted communications by synchronizing two FOCS—one for the sender and one for the receiver. An innovative optimization method, the artificial Harris hawks optimization (HHO), is employed to optimize the observer's parameters, eliminating the need for random parameter selection. The HHO method is chosen for its superior performance in solving convex optimization problems, minimizing the mean square error (MSE) between the states of the emitter and receiver. The transmitter system is configured with a secret message injected into the third derivative of the chaotic system, while the receiver system uses an SBS-SMO to estimate the state variables and the secret message. The HHO algorithm is used to determine the optimal parameters for the SBS-SMO, ensuring successful synchronization and accurate message recovery. The effectiveness of the proposed method is demonstrated through numerical simulations and real-time experiments using an Arduino microcontroller and electronic components. The results show that the proposed scheme successfully recovers the secret message, including signals, voice, and images, with high accuracy. The security of the communication is further evaluated by modifying the initial conditions and transmission sequences, which results in the loss of the message. The study concludes that the proposed method provides robust security and is ready for practical applications, with future work focusing on transmitting secure images and improving the synchronization process using advanced algorithms.This paper presents a novel approach to secure communication using Fractional-Order Chaotic Systems (FOCS) and a Step-By-Step Sliding-Mode Observer (SBS-SMO). The study aims to enhance the security of encrypted communications by synchronizing two FOCS—one for the sender and one for the receiver. An innovative optimization method, the artificial Harris hawks optimization (HHO), is employed to optimize the observer's parameters, eliminating the need for random parameter selection. The HHO method is chosen for its superior performance in solving convex optimization problems, minimizing the mean square error (MSE) between the states of the emitter and receiver. The transmitter system is configured with a secret message injected into the third derivative of the chaotic system, while the receiver system uses an SBS-SMO to estimate the state variables and the secret message. The HHO algorithm is used to determine the optimal parameters for the SBS-SMO, ensuring successful synchronization and accurate message recovery. The effectiveness of the proposed method is demonstrated through numerical simulations and real-time experiments using an Arduino microcontroller and electronic components. The results show that the proposed scheme successfully recovers the secret message, including signals, voice, and images, with high accuracy. The security of the communication is further evaluated by modifying the initial conditions and transmission sequences, which results in the loss of the message. The study concludes that the proposed method provides robust security and is ready for practical applications, with future work focusing on transmitting secure images and improving the synchronization process using advanced algorithms.