This paper proposes a new LMI approach to establish a more relaxed sufficient condition for quadratic stabilization of T-S fuzzy systems. The proposed conditions not only improve the conservativeness but also include previous results as special cases. Extending the proposed idea to deal with the observer-based H∞ control problem, two conditions that guarantee the existence of the H∞ controller based on fuzzy observers are also developed. The conditions are more relaxed than the existing one and ensure the designed fuzzy H∞ controller achieving a better performance. The validity and applicability of the proposed approach are successfully demonstrated in the control of a continuous-time nonlinear system.