Bio-Futures for Transplanetary Habitats (BFfTH) is a Special Interest Group within the Hub for Biotechnology in the Built Environment that aims to explore and enable interdisciplinary research on transplanetary habitats and habitats within extreme environments through an emphasis on the bio-social and biotechnological relations. BFfTH organized the online and onsite networking symposium Bio-Futures for Transplanetary Habitats to examine how emerging biotechnologies, living materials, and more-than-human life can be implemented in habitat design and mission planning. The two day symposium aimed to serve as a catalyst in establishing an international network of collaborators across industry, academia and the private sector. It also aimed to support the development of novel methodologies to move beyond discipline-specific approaches in order to address and interrogate emerging questions surrounding potential transplanetary habitats and habitats in extreme environments. The symposium was divided into five sessions which hosted a minimum of three speakers each, these sessions were: Mycelium for Mars, Plants and Agriculture, Sustainable Habitats and Travels, Artistic Approach to Extremes Habitats, and Novel Biotechnologies for Space Habitats. This paper presents key outcomes from the symposium sessions, moderated panel, and informal discussions. The trends in ongoing research are identified and summarized following the use of biotechnology and bio-design to ensure and support safety, sustainability, habitability, reliability, crew efficiency, productivity and comfort in extreme environments both here on Earth and off-world. Moving beyond pure design and engineering innovation, the outcomes of this symposium also further interrogates sociotechnical imaginaries. Biodesign-based and biotechnologically-enabled transplanetary futures are investigated to understand how we want these futures to behave, feel and be experienced. The symposium hosted a wide range of topics including: innovative material-driven processes for the design of transplanetary habitats; socio-political concerns or ethical implications to be taken into account; technology transfer and transitioning towards a sustainable built environment on Earth; multi-species narratives and relations to sustain human and other-than-human life in transplanetary habitats; sociotechnical considerations in propagating and sustaining Earthbound life beyond Earth environments; and sustainable living on Earth through a holistic systems thinking approach. BFfTH further reflects on what potential bio-social and biotechnological research is needed to sustain life in an extraterrestrial environment in the future and how it can help with transitioning towards a more sustainable built environment here on Earth in the present.