A single liquid protein beverage dispensing system is disclosed that automatically mixes a drink mix powder, such as protein powder, with a chilled or ambient temperature liquid, preferably water, to form a mixed protein liquid beverage or drink of uniform consistency. The system can provide for different amounts of water from a reservoir to be mixed with at least one or up to three different types of protein powders and then dispensed into a beverage container. The system has an electronic user interface by which the user can make various combinations of liquid amounts and powder selections to prepare a mixed drink. An advantageous feature of the system is that, because of the density and moisture content of every powder, the system provides vibration assistance for the powders to agitate during dispensing which prevents clumping of the powder in the liquid during mixing of the powder with the liquid to provide a beverage admixture of uniform consistency.