Magnetostrictive iron-gallium alloys, known as Galfenol, are a recent class of smart materials with potential in energy harvesting applications. Unimorph energy harvesters consisting of a Galfenol beam bonded to a passive substrate are simple and effective, but advanced models are lacking for these smart devices. This study presents a finite element model for Galfenol unimorph harvester systems. Experiments considering various design parameters such as pick up coil size, load resistance, beam thickness ratio, and bias magnetic field strength are conducted to guide and validate the modeling effort. If the free length of the Galfenol unimorph beam is considered as the effective length, the maximum average power density, peak power density, and open-circuit voltage amplitude achieved in experiments are 13.97 mW/cm3, 35.51 mW/cm3, and 0.66 V, respectively. By only considering the length of Galfenol surrounded by the pickup coil, the maximum average power density and peak power density are 23.66 mW/cm3 and 60.14 mW/cm3, respectively.