The quality of a product fabricated using the powder-based additive manufacturing (AM) process depends on the flow characteristics of the feed-stock particles. Controlled flow is important for homogeneous distribution of the powder particles. One way to enhance this control is by using vibration-assisted flow. In this work, the influence of external mechanical vibration on the powder flow is investigated experimentally and using discrete element simulations. An experimental setup with a shaker attached directly to a glass hopper was used to study the influence of vibration amplitude, applied transversely to the flow direction, on the mass flow rate of spherical particles. The data showed an optimal amplitude of vibration at which the mass flow rate, out of the hopper, was maximum. To understand this, a discrete element simulation model mimicking the particle flow was developed. The model results showed that a minimum amount of vibration amplitude was required to sustain and trigger the flow. The flow rate increased with an increase in vibration amplitude, similar to experimental data, up to an optimal value of vibration amplitude and decreased with a further increase in amplitude. An analysis of simulation data showed that the resident time of particles in the hopper decreased and then increased with amplitude. At higher amplitudes, particles spent more time moving horizontally, along the vibration direction, rather than vertically along the flow direction, thus explaining the optimal value of the amplitude. The research facilitates the effective use of mechanical vibration to enhance powder flow for powder-based AM applications. The method can further be extended to non-spherical particles or multi-material particles.