With the rapid development of bio-based polymers, polybenzoxazine derived from renewable resources has been widely investigated. However, there are few reports on the functional application of bio-based polybenzoxazine based on the special chemical structures of renewable compounds. In this work, an easy approach to prepare the polybenzoxazines with varied thermomechanical properties and excellent marine antifouling performance from renewable resources is presented. After a variety of main-chain-type benzoxazine polymers (MCBPs) were synthesized from the renewable daidzein, furfurylamine, polyetheramine, and paraformaldehyde, their chemical structures were identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy ( 1 H NMR). Then, their curing behaviors were monitored by differential scanning calorimetry and rheological tests. Results revealed that the cross-linked MCBPs with varied thermomechanical properties could be easily prepared by adjusting the molar ratio of polyetheramine and furfuramine. Notably, these cured MCBP films demonstrated excellent antibacterial and algaecidal properties due to the presence of daidzein and furan units. This work first presents the new application prospect of bio-based MCBPs, for example, in marine antifouling coatings., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)