Intumescent coatings formulated with coconut fiber (CCN), wood waste (MDP), and peach stone (PEA) biomasses were tested. Different formulations with variable concentrations of biomasses were carried out. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) confirm that lignin and cellulose are constituents of these compounds. Fire-resistance testing confirms the percentage of 9% in dry mass as the optimal amount of CCN and MDP, while 6% is ideal for PEA. IR thermal images show the thermal protection and high expansion on the intumescent coatings (600% for CCN9, 1300% for MDP9, and 1600% for PEA6) and corroborate the data of the thermocouple. The maximum temperatures on the back of the substrate were 120 degrees C with biomass-based intumescent coatings and 474 degrees C for uncoated steel. TGA and X-ray diffraction of the coatings confirm the formation of stable oxides. Optical microscopy images show the presence of pores in the char layer.