Plastics play important roles in modern life and currently the development of plastic recycling is highly demanding and challenging. To relieve this dilemma, one option is to develop new sustainable bioplastics that are compatible with the environment over the whole material life cycle. We report a sustainable bioplastic made from natural DNA and biomass-derived ionomers, termed as DNA plastics. The sustainability involves all aspects of the production, use, and end-of-life options of DNA plastics: (1) the raw materials are derived from biorenewable resources; (2) the water-processable strategy is environmentally friendly, not involving high-energy consumption, the use of organic solvents, and the production of byproducts; (3) recyclable and nondestructive use is achieved to significantly prolong the service lifetime of the plastics; and (4) the disposal of waste plastics follows two green routes including the recycling of waste plastics and enzyme-triggered controllable degradation under mild conditions. Besides, DNA plastics can be "aqua-welded" to form arbitrary designed products such as a plastic cup. This work provides a solution to transform biobased hydrogel to bioplastic and demonstrates the closed-loop recycling of DNA plastics, which will advance the development of sustainable materials.