Abstract Solar‐driven interfacial water evaporation is a green and energy‐efficient water treatment technology with diverse applications in desalination, steam power generation, and agricultural irrigation. Biomass materials have gained significant attention in solar evaporator engineering due to their unique structure, low cost, and ease of adjustment. With enhanced light absorption and high thermal conductivity, biomass materials can improve evaporation efficiency substantially, thus providing opportunities in solar evaporation applications. Therefore, in this critical review, the operating principles and design concepts of solar evaporators are first briefly discussed in terms of the photothermal conversion mechanism. Subsequently, the superiority of biomass materials in solar evaporator design is described in detail from the types of biomass and their structural properties at micro/macro scales. The design principles and corresponding performance enhancement strategies for biomass‐based evaporators are also highlighted, including material selection, structural design, and thermal management techniques. Meanwhile, recent advances in biomass‐based evaporators for several cutting‐edge applications are comprehensively discussed. This review can provide a comprehensive reference for the relevant researchers to advance the research and application of biomass‐based solar evaporators and to promote their wide application in the field of green technology.