Flexible and wearable energy technologies are becoming progressively smaller and more compact as a result of ever-increasing breakthroughs and advances in the area of energy research. Flexible and wearable solar cells are indeed very essential in systems that need energy harvesting in wearable applications. Since conventional silicon-based solar cells are not enough to meet the demands of flexible technology, the majority of the flexible and wearable solar cells produced today are made of organic or hybrid materials, as well as inorganic perovskite materials. Meanwhile, rising energy consumption and increased environmental consciousness have brought attention to the need for green and renewable energy. Therefore, combining flexible solar cells with energy storage devices may aid in the development of self-sustaining systems that not only provide potential solutions to the environmental problems, but also allow the whole system to function without the need for external power. In this chapter, the development and latest advances in flexible and wearable energy generation systems are discussed with emphasis on dye-sensitized solar cells (DSSCs), organic, polymers, and perovskites for wearable and flexible photovoltaics. With the rapidly emerging flexible and wearable smart devices, compact, low-cost, mechanically flexible thin-film wearable sources of energy featuring superior power densities, long-term stability, reliability, and operating safety are considered indispensable.