This study investigates the eco-friendly synthesis of TiO2 NPs using Melastoma malabathricum fruit extract and lime juice as natural reducing and capping agents. The extract was prepared by macerating the sample in ethanol. TiO2 NPs were synthesized via the sol–gel method with five variations: one control sample using ethanol only and four samples incorporating plant extracts with varying lime juice concentrations. The results confirmed the formation of pure anatase-phase TiO2 with crystallite sizes decreasing from 18.17 to 12.43 nm. Optical analysis revealed bandgap energies of 3.09-3.14 eV, suitable for dye-sensitized solar cell (DSSC) applications. The field-emission scanning electron microscopy (FESEM) images revealed more uniform, smaller particles in the capped samples, as supported by the particle-size distribution data. energy-dispersive X-ray spectroscopy (EDX) confirmed that the elemental composition is close to stoichiometric TiO2. Electrochemical analysis indicated that the sample using Melastoma malabathricum fruit extract exhibited superior photovoltaic performance (power conversion efficiency (PCE) = 3.12%) owing to enhanced charge injection, despite a shorter electron lifetime (55 ms). Additionally, samples using Melastoma malabathricum fruit extract and lime juice exhibited improved charge retention (τe = 205-274 ms), despite their moderate efficiencies (2.26-2.49%). This study demonstrates the significant potential of tropical plant-mediated synthesis for developing sustainable, high-performance DSSC photoanodes, with performance governed by careful optimization of the composition of natural capping agents. © 2026 Faculty of Engineering, Universitas Indonesia. All rights reserved.