In the context of intensifying global energy and environmental pressures, the expansion of alternative renewable energy sources has become increasingly important, with plant biomass remaining one of the most accessible options. For ecological engineering and national energy security – especially in countries undergoing reconstruction – identifying high-yield, climate-resilient bioenergy crops is critical. Sweet sorghum stands out as a species capable of producing large volumes of energy-rich biomass within a single growing season, the yield of which can be further increased through optimized cultivation technologies. This study provides the first production-scale data for Ukraine under the 2021–2023 climatic conditions, assessing the effect of foliar feeding on biomass formation and energy productivity. The field experiment involved the registered sweet sorghum variety Favorit, tested under four foliar fertilization treatments: control (no feeding), application at the seedling stage, at the tillering stage, and combined application at both stages, using Kristalon Special. Biometric measurements and biomass yield determinations were carried out according to approved scientific and methodological standards. Across three years, foliar feeding significantly increased plant biometric parameters compared to the control, particularly the number of internodes and leaves per plant, as well as the length and width of the upper leaf. Green mass yield showed a strong positive correlation with these morphological traits (r > 0.71), while dry biomass yield demonstrated a moderate correlation (r = 0.48–0.62). Foliar fertilization increased the total accumulated energy in sweet sorghum biomass from 596.6 to 665.0 GJ/ha, with the energy efficiency coefficient ranging from 1.37 to 1.84. The highest yields of green mass (97.6 t/ha) and dry biomass (33.8 t/ha) were obtained when Kristalon Special was applied twice – at the seedling and tillering stages. In practical terms, these findings demonstrate that optimized foliar nutrition can substantially enhance the productivity and energy efficiency of sweet sorghum, supporting its wider adoption in sustainable land-use systems and decentralized bioenergy production.