Zero waste multistage utilization of biomass from Ginkgo biloba branches (GBBs) was achieved through extraction of bioactive components, analysis of antioxidant and antibacterial activities, preparation and composition of pyrolyzate, adsorption and reuse of modified biochar. The results showed that GBBs had abundant bioactive components for potential application in the industry of food, chemical raw materials and biomedicine. Especially, the bioactive compounds in acetone extract (10 mg/mL) of GBBs identified by DPPH and ABTS had free radical scavenging abilities of 92.28% and 98.18%, respectively, which are equivalent to Vitamin C used as an antioxidant in food additives. Fourier Transform Infrared and X-Ray Diffraction analysis showed that carboxymethyl cellulose (CMC) and magnetic Fe3O4 were successfully incorporated into raw biochar (RB) to form CMC-Fe3O4-RB nanomaterial. Scanning electron microscopy and X-Ray Diffraction spectroscopy displayed Fe, C, and O existed on the surface of CMC-Fe3O4-RB. Compared with RB, CMC-Fe3O4-RB had a larger specific surface area, pore volume and pore size. Meanwhile, nanomagnetic CMC-Fe3O4-RB solved the problem of agglomeration in traditional magnetized biochar production, and improved the adsorption capacity of Pb2+, which was 29.90% higher than that of RB by ICP-OES. Further, the Pb2+ (10 mg/L) adsorption capacity of CMC-Fe3O4-RB reached the highest level in 2 h at the dosage of 0.01 g/L, and remained stable at 52.987 mg/g after five cycles of adsorption and desorption. This research aided in the creation of a strategy for GBBs zero waste multistage usage and a circular economic model for GBBs industry development, which can be promoted and applied to the fields of food industry and environment improvement.