Semifusinite and fusinite macerals are formed through carbonization of plant material in naturally occurring wildfires. Both macerals, belonging to the inertinite maceral group, are carbon-rich and oxygen-poor, and are typical constituents of charcoal. The charring of plant material into charcoal serves as nature’s method for storing carbon over geological timescales. The permanence and stability of carbon in biochar formed by pyrolysis of biomass are determined by its degree of carbonization, and long-term storage in soil assumes that the biomass has been completely transformed into inertinite biochar. Inertinite biochar is thought to have a structural composition comparable to natural fusinite, whereas less carbonized and less stable biochar is similar to semifusinite. In this study, micro-Raman spectroscopy was employed to examine the structural composition of 16 biochar samples produced at different temperatures from various lignocellulosic feedstocks, as well as one natural semifusinite isolated from a coal deposit. The estimated carbonization temperatures, representing the actual internal heating temperatures experienced by the biomass, ranged from 326–825 °C. The micro-Raman results of the biochar samples included in this data release were compared with previously published micro-Raman data on semifusinite and fusinite.