Liquid droplet impact on a soft substrate plays an important role in many applications. Even though certain research has been conducted in this field, only few of them were focused on droplet impact over soft rough surfaces and the mechanisms of liquid-soft surface interactions remain elusive. Here, we report our numerical simulation of liquid droplet impact dynamics on a micropillar-arrayed soft surface by the finite volume method. As such, the volume of fluid method is coupled with the Navier–Stokes equation solver to build and track the evolution of the interface between two immiscible fluid phases. From an ad hoc point of view, the micropillared substrate is composed of interstitial gaps into the otherwise intact soft material, of which the viscoelastic properties can be quantified by gap density. Based on the five-parameter generalized Maxwell model, the viscoelastic properties of the micropillared substrate can be approximated by its equivalent elastic response in the Laplace–Carson space, which captures both stress relaxation and creep behaviors in response to external impetus. Instead of resorting to each individual micropillar’s property and response, which is also computationally prohibitive, the bulk strain of the micropillared substrate in the real space is obtained by the inverse Laplace–Carson transform to evaluate its averaged bulk response. Also, the substrate deformation velocity in the bulk normal direction at each time step is acquired, which is treated as the Dirichlet boundary condition to the fluid fields including the impinging liquid droplet and the ambient gas. Moreover, parametric studies have been conducted to investigate the effects of various factors such as impact velocity, ambient pressure and surface tension coefficient on splash threshold and magnitude. Overall, the splash magnitude from our numerical simulation has an excellent agreement with that predicted by the Kelvin-Helmholtz instability theory. By leveraging the Laplace–Carson transform in the fluid-viscoelastic solid interactions, our numerical simulation methodology captures the main features of droplet impact dynamics on microstructured viscoelastic surfaces by virtue of mechanically averaged responses.