The rapidly accumulating waste of rigid polyurethane (PU) foam has garnered global attention. Glycolysis has emerged as a promising method for recycling waste PU foam, showing remarkable promise for propelling the development of the bio-based polymer industry. Crude glycerol was used to effectively degrade waste PU foam, synthesizing a single-phase biopolyol with suitable physicochemical properties as a secondary raw material for new rigid PU products. The regenerated foam exhibited excellent degradation performance even after multiple recycling cycles. The waste PU foam was depolymerized using crude glycerol, and the breaking of carbamate bonds was monitored using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gas chromatography-mass spectrometry (GC–MS), confirming the glycolysis process. A novel flame-retardant PU foam was fabricated using the obtained biopolyols. The compressive strength of this foam reaches 284 kPa, with a density of 0.044 g·cm−3 and a thermal conductivity of 0.037 W·m−1·K−1. The PU foam attains a limiting oxygen index of 27.8 %, and vertical combustion tests have verified that it can achieve a V-0 rating. A techno-economic evaluation of the PU foam process through glycolysis with crude glycerol provided theoretical insights for developing biopolyol processes.