This work develops asymptotic properties of randomly switching and time inhomogeneous dynamic systems under Brownian perturbation with a small diffusion. The switching process is modeled by a continuous-time Markov chain, which portraits discrete events that cannot be modeled by a diffusion process. In the model, there are two small parameters. One of them is e associated with the generator of the continuous-time, inhomogeneous Markov chain, and the other is δ = δe signifies the small intensity of the diffusion. Assume e → 0a ndδe → 0a se → 0. This paper focuses on large deviations type of estimates for such Markovian switching systems with small diffusions. The ratio e/δe can be a nonzero constant, or equal to 0, or ∞. These three different cases yield three different outcomes. This paper analyzes the three cases and present the corresponding asymptotic properties.