This paper addresses the adaptive event-triggered finite-time H 8 control problem of Takagi-Sugeno fuzzy semi-Markovian jump systems with immeasurable premise variables. Firstly, different from some existed works, the restrictions of measurable system states and measurable premise variables of nonlinear plant are removed and the fuzzy observer is designed to estimate unmeasurable system states. Then, a novel adaptive event-triggered scheme is firstly proposed to reduce the number of data transmission while ensuring the reliable system performance. Subsequently, the asynchronous problem about premise variables, namely, the premise variables of fuzzy system are not consistent with premise variables of fuzzy event-triggered controller is dealt with by utilizing an asynchronous method. By applying the delay system method, free-weighting matrix approach and slack matrix variables, novel sufficient conditions are derived to guarantee the finite-time H 8 performance of the closed-loop system, where the nonlinear terms caused by network-induced delay and partly unknown transition rates can be tackled by using suitable method. Finally, the single-link robot arm system is presented to affirm the efficiency of the obtained theoretical results. (c) 2022 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.