Gas-liquid-solid mixing is essential in a wide range of chemical, pharmaceutical and bioprocessing applications, yet the hydrodynamic behavior of MaxBlend impellers in three-phase systems remains largely unstudied through computational approaches. This work presents a novel CFD investigation of a three-phase mechanically agitated reactor equipped with a MaxBlend impeller. An Eulerian–Eulerian multiphase model, incorporating sliding mesh and appropriate drag and turbulence models, is used to simulate flow dynamics in a Newtonian system. The study focuses on evaluating key hydrodynamic and transport parameters, such as velocity fields, solid and gas holdup, impeller speed, and power consumption, across various operating conditions. The analysis aims to characterize the impeller’s ability to promote efficient and effective mixing. The developed CFD framework also sets the stage for future extensions to non-Newtonian fluids and the estimation of local and global mass transfer coefficients. Additional simulations will explore the effects of fluid rheology, gas flow rates, and particle properties on mixing performance. This study establishes a complete numerical framework for understanding flow behavior in gas-liquid-solid mechanically agitated reactors, addresses a critical gap in the application of MaxBlend impellers and serves as a foundation for future experimental validation and scale-up investigations. These insights are intended to support process optimization in industrial applications where three-phase mixing plays a critical role.