The growing demand for renewable energy and resource-efficient waste management has intensified interest in alternative lignocellulosic feedstocks. This study investigates the thermal decomposition behavior and proximate composition of eight cultivars of Camellia japonica flowers, a widely cultivated but underutilized ornamental species. Thermogravimetric analysis was employed to assess weight loss dynamics under controlled heating, while derivative thermogravimetry and heat flow data provided further insights into decomposition stages and energy release patterns. All samples exhibited a characteristic three-step degradation: (i) initial moisture loss below 120 °C, (ii) an active devolatilization stage between 200 and 400 °C associated with hemicellulose and cellulose breakdown, and (iii) a final slow degradation phase above 450 °C, typically attributed to lignin decomposition and char formation. Among the cultivars studied, Carolyn Tuttle and Conde de la Torre showed the highest volatile matter contents (97.34- 97.26%), indicating strong potential for pyrolysis-based valorization. Conversely, Elegans Variegated exhibited the highest apparent fixed carbon retention (−0.15%), with a slightly lower volatile fraction (96.59%). Ash content was consistently low. The average volatile matter content across all samples exceeded 96%, confirming the high organic fraction that is typical of floral biomass. Fixed carbon values remained within a narrow range (−0.01% to −0.15%), suggesting minimal residual char formation and indicating suitability for fast pyrolysis or combustion with limited solid waste output. These findings highlight Camellia japonica flowers as a promising biomass resource with favorable thermochemical properties. Their high volatility, low ash contents, and consistent thermal profiles support their inclusion in circular bioeconomy models and localized bioenergy strategies, particularly in regions with substantial ornamental plant waste.