Due to the ever-increasing population, plastic usage has exponentially increased in the last decade. Its continual usage leads to its accumulation in landfills and aquatic environments, which adversely affects all forms of life and the environment. Only 9% of plastic is successfully recycled. One of the solutions to this problem is use of production of bioplastic. Bioplastic is a type of plastic that is biodegradable and bio-based. One of them is bioplastic from algal cells. Algal cells are unicellular or multicellular photosynthetic organisms. Algal bioplastic can be produced using algal biomass or its secondary metabolites. Polyhydroxybutyrate (PHB) is a biopolymer that is produced by algae as well as bacteria. Its biodegradable, recyclable, and biocompatibility qualities are principal strengths. Microalgae and cyanobacteria are used for PHB production. Its breeding can be done on sewage water and industrial effluents. It is an established fact that it has zero negative environmental impacts. Their short doubling time makes them excellent raw material sources for bioplastic production. This chapter addresses PHB (polyhydroxybutyrate) production by algae, biosynthetic pathways, extraction methods, technical aspects, current applications, and market trends.