The necessity of developing a green, circular, and sustainable process to produce high bio-content building materials has directed current research trends. In this paper, we introduce a novel high bio-content-based polyurethane (BPU) nanocomposite foam that is prepared using 100 % bio-polyol and nanocellulose fiber (CNF). Both the bio-polyol and CNF are obtained from bamboo biomass to limit the environmental footprint of petroleum-derived materials. In addition, environmentally-friendly non-halogen flame retardants (FRs) are incorporated into BPU nanocomposite to enhance fire safety, mitigate fire risks, and advance the development of fire-resistant insulation materials and construction technologies. The BPU and BPUC