Bacteriorhodopsin (bR) is a trans-membrane photoactive protein found in the purple membrane of Halobacterium salinarum, which can tolerate extreme environmental conditions. Due to its capacity for light-activated proton pumping and color switching, this protein has been applied in wide range of fields, including solar cells, fuel cells, biosensors, artificial retinas, optical devices, nanosensors, storage devices, camouflage, bio-defense, holographic memory, and security ink. The photocycle of bR can be modified through mutation, which is the subject of this review. As bR has high stability and proton-release characteristics, it is an attractive candidate for use in the production of hydrogen through the splitting of water. Solar hydrogen production and storage using bR-based photoelectrodes could play important roles in a sustainable economy based on renewable energy. We summarize recent advances in bR-based hybrid electrodes for solar cells, water-splitting devices, and fuel-cell applications and describe recent efforts in this area with a focus on materials-related considerations. Emerging applications in sensors and security inks are also discussed to apprise researchers of the potential and challenges presented by bR.