We report on the implementation of thin atomic layer deposited coatings for environmental protection and reflectivity enhancement of Al-based micromirror devices. The reflectance characteristics of HfO2 and SiO2 thin layers on Al surfaces has been simulated by Rigorous Coupled-Wave Analysis (RCWA). Reflectance enhancement, especially in the 420–675 nm wavelength region, has been predicted by fine-tuning the layer thickness in HfO2/SiO2 dual layer stacks. This engineered solution has been developed and then implemented on real micro-electro-mechanical system (MEMS) devices demonstrating an enhancement of the reflectivity. Our approach suggests that atomic layer deposition is a valid method for both protecting and enhancing the performances of reflective surfaces of micro-opto-electro mechanical systems.