This paper designs a control law to maintain the temperature in the jacket of a continuous stirred tank reactor (CSTR). The standard mathematical model describing the reactor operation is extended by introducing the actuator’s dynamics. The state-space and control constraints are considered by a nonlinear change of the variables of the plant’s initial model using linear sat functions. In the transformed system, these constraints are considered by feedback control law design. The block approach allows linearizing the feedback control law by sequentially solving the first-order design subproblems. Under incomplete information on the state vector and the effect of exogenous disturbances, an observer of the state vector and disturbances is constructed to estimate the unknown signals with a given accuracy. The effectiveness of the proposed approach is illustrated by simulating the CSTR–DC motor system in MATLAB.