This paper presents modeling and analysis of a piezoelectric mounted rotary flexible beam that can be used as an energy scavenger for rotary motion applications. The energy harvester system consists of a piezoelectric bimorph cantilever beam with a tip mass mounted on a rotating hub. Assuming Euler–Bernoulli beam equations and considering the effect of a piezoelectric transducer, equations of motion are derived using the Lagrangian approach followed by relationships describing the harvested power. The equations provide a quantitative description of how the hub acceleration and gravity due to the tip mass contribute power to the energy harvester. In particular, expressions describing optimum load resistance and the maximum power that can be harvested using the proposed system are derived. Numerical simulations are performed to show the performance of the harvester by obtaining tip velocities and electrical output voltages for a range of electrical load resistances and rotational speeds. It is shown that by proper sizing and parameter selection, the proposed system can supply enough energy for operating wireless sensors in rotating mechanisms such as tires and turbines.