In this study, hydrothermal carbonization of carrot juice was conducted at 180 °C for 6 hours, followed by annealing at 500 °C for 6 hours. In the absence of a catalyst, hydrothermal carbonization of carrot juice produced hollow and solid carbon microspheres (CMS) with diameters ranging from 0.3 to 4.0 µm. SEM and TEM images of the CMS showed various morphologies and sizes. X-ray diffraction and Raman spectroscopy indicated the CMS had a disordered graphitic structure. A HAADF micrograph showed that although the majority of the CMS in this study were hollow, there were also solid spheres which had not previously been reported for hydrothermal carbonization. STEM EDS mapping of a solid CMS indicated approximately 95 wt% of C with traces of N, O, Si, P, S, Cl and K. The effect of the starting precursors on the hard sphere formation mechanism is discussed.