This work presents an observer-based adaptive control approach for time-delay chaotic systems with uncertainty. The chaotic system is initially expressed with the Takagi-Sugeno (T-S) fuzzy model. The de-sign of the adaptive fuzzy observer is introduced based on the assumptions of chaotic system proper-ties. Next, the design principle is applied to stabiliza-tion and tracking problems. Based on Lyapunov's stability analysis, the sufficient conditions for synthe-sizing a stable observer and controller are expressed in the form of adaptive updating laws and linear ma-trix inequality (LMI). Computer simulation verifies the system, controlled by the proposed method, per-forms well.