We synthesized a crude extract of Sappanwood (Caesalpinia sappan L.) and incorporated the ZnO nanoparticles (ZnO-NP) as the natural light -harvesting material (dye). The maceration method was used to extract crude brazilein from Sappanwood. The physical and chemical properties of the crude brazilein extract (CBE) and CBEincorporated ZnO-NP were investigated using a UV-Vis spectrometer, XRD, FTIR, and LSV. The performance of the natural dye in the DSSC was investigated concerning the immersion time of 6, 12, 18, and 24 hours, using current -voltage measurement. ZnO-NP addition led to an increase in the concentration of the aromatic functional group. The UV-Vis measurement of CBE showed the most intense peak at 490 nm. A red shift was observed in the absorbance spectrum of CBE -incorporated ZnO-NP. The reduction current was observed for all samples where its value decreased as the immersion time was longer. The I -V measurements showed that immersion time affected both current density (Jsc) and open -circuit voltage (Voc), as the longer immersion time resulted in higher Jsc and Voc leading to higher overall conversion efficiency (eta), this applied for both CBE and CBE -incorporated ZnO-NP. The utilization of CBE -incorporated ZnO-NP highly improved the photovoltaic properties of the DSSC cells for all immersion time, specifically for 24 hours, the Jsc, Voc, and eta values increased as much as 135.7%, 60.4%, and 550% respectively, reaching the highest efficiency of 2.6%. The above results confirmed that Sappanwood can be utilized as an efficient, low-cost cost, and environmentally friendly source of natural dye for DSSC application. Future development will be directed toward purifying the extract and elaboration of other metals as stabilizing agents.