This paper is focused on the design of a nonlinear observer for a rotatory machine with noise-affected output. It is assumed that the system is subject to bounded perturbations, and the original linear model of the machine is reformulated as a nonlinear system to include the desired signals to be estimated, namely, the velocity and load torque. The proposed observer leverages the so-called algebraic state-dependent Riccati equation to provide a robust estimation. Lyapunov analysis guarantees the convergence of the estimation error to a “κ zone”. The proposed observer’s effectiveness is assessed through convincing numerical simulations and real-time experiments.