In this paper, we mainly address the issue of finite‐time stochastic boundedness (FTSB) and finite‐time stochastic dissipation for semi‐Markovian jump systems (SMJSs) with generally uncertain transition rates (TRs). Firstly, by resorting to linear matrix inequities (LMIs), some sufficient conditions on FTSB for SMJSs with uncertain TRs are introduced, which includes two cases. Then, dissipative control is developed and a state feedback controller is designed to ensure the FTSB of the closed‐loop system by solving a series of LMIs. Finally, two examples are used to illustrate the results.