Negative emissions technologies that can remove carbon dioxide from the atmosphere are a critical tool to limit global temperature rise and ocean acidification. Bioengineering capabilities have not been sufficiently assessed or utilized for the development of negative emissions technologies. Bioengineering holds the potential to improve the efficiency of some existing technologies and to create new methods of carbon removal. I review existing technologies to assess how bioengineering could improve them, focusing on technologies that could achieve at least 1 Gt of CO₂ removal per year. I also investigate and describe potential new methods of carbon removal that leverage bioengineering. Key questions for additional research are identified, as are key engineering targets for the development of improved negative emissions technologies. This evaluation of potential high-impact R&D work is intended to provide an initial roadmap for the development of bioengineered negative emissions technologies that are scalable, sustainable, and can remove gigatons of CO₂ from the atmosphere.