Galloping of structures such as transmission lines and bridges is a classical aeroelastic instability that has been considered as harmful and destructive. However, there exists potential to harness useful energy from this phenomenon. This paper focuses on harvesting wind energy that is being transferred to a galloping beam. The beam has a rigid tip body with a D-shaped cross section. Piezoelectric sheets are bonded on the top and bottom surface of the beam. During galloping, vibrational motion is input to the system due to aerodynamic forces on the D-section, which is converted into electrical energy by the piezoelectric (PZT) sheets. The relative importance of various parameters of the system such as wind speed, material properties of the beam, electrical load and beam’s natural frequency are discussed. Experimental and analytical investigations of dynamic response and power output are performed on a representative device. A maximum output power of 1.14 mW was measured at a wind velocity of 10.5 mph on a prototype device of length 235 mm and width 25 mm. A potential application for this device is to power wireless sensor networks on outdoor structures such as bridges and buildings.