Summary: This paper provides an improved result over that in

*X. Liu* and

*Q. Zhang* [New approaches to

${H}_{\infty}$ controller designs based on fuzzy observers for T-S fuzzy systems via LMI. Automatica 39, 1571–1582 (2003;

Zbl 1029.93042)] for the problem of observer-based

${H}_{\infty}$ control for nonlinear systems in Takagi-Sugeno (T-S) fuzzy model. It contributes in three aspects: (i) The present result is less conservative than that in

*X. Liu* and

*Q. Zhang* [loc. cit.]; (ii) The present strict LMI method is a single step approach which overcomes the drawback of a two-step approach in

*X. Liu* and

*Q. Zhang* [loc. cit.]; (iii) The matrix dimensions are largely reduced compared with the corresponding ones in Liu and Zhang [loc. cit.].