Rotational energy is abundant in numerous industrial applications, spanning from miniature devices like watches to massive installations such as offshore wind turbines. As wireless sensing technology continues to evolve, there is a growing interest in developing self-sustaining energy sources for wireless sensors used in rotating systems. This research aims to expand the operational bandwidth of energy harvesters by integrating a dual-beam structure and nonlinear magnetic interactions to enhance low-frequency, high-efficiency energy harvesting during rotary motion. Both theoretical and experimental approaches are employed to assess the influence of nonlinear magnetic forces on the performance of the harvester in rotary environments. The study begins with the design of a nonlinear energy harvester featuring parallel-aligned double beams in rotational motion. This configuration is shown to be highly efficient, capable of effectively capturing energy across a broad frequency spectrum from 15 to 35 rad/s. To further improve low-frequency energy harvesting, the research extends to the modeling and analysis of a vertically arranged nonlinear energy harvester in rotational motion. The findings reveal that this vertical arrangement significantly boosts the harvester's efficiency at low frequencies, particularly within the range of 10–37 rad/s. Experimental investigations are conducted to corroborate the theoretical predictions, confirming that the designed energy harvester exhibits desirable characteristics for low-frequency broadband energy harvesting. These results underscore the potential of the proposed harvester designs to meet the energy requirements of wireless sensors in various rotating machinery applications, thereby advancing the field of self-powered sensor technology.