Transforming invasive water hyacinth into densified solid fuel offers a route to couple aquatic-weed management with renewable energy recovery. This study evaluated an integrated configuration combining temperature-controlled torrefaction in a vertically arranged, closed-loop vibrating reactor with downstream binder-assisted pellet densification. Raw biomass was washed, chopped to 10–20 mm, pre-dried to approximately 15% moisture, and torrefied at 240, 260, 280, 300, and 320 °C at a biomass feed rate of 300 g h⁻¹, with three independent runs at each temperature. Increasing torrefaction severity raised mean higher heating value (HHV) from 19.87 to 26.26 MJ kg⁻¹ while mean solid yield declined from 85.33% to 59.27%. The trade-off was most pronounced above 300 °C: increasing temperature from 300 to 320 °C provided only a 0.98 MJ kg⁻¹ HHV gain but caused an additional 6.86-percentage-point loss in solid yield. Product-side retained solid energy ranged from 15.56 to 16.95 MJ kg⁻¹ of initial feed, and propagated uncertainty analysis showed that small differences among several conditions should be interpreted descriptively rather than as statistically demonstrated advantages. Pelletization improved physical handling characteristics. Binder-free pellets exhibited a pellet density of 979.14 ± 45.00 kg m⁻³, a bulk density of 585.14 ± 35.00 kg m⁻³, and mechanical durability of 93.15 ± 1.50%. Cassava starch produced the highest pellet density (1106.19 ± 35.00 kg m⁻³), whereas used engine oil produced the highest bulk density (725.12 ± 85.00 kg m⁻³). Mechanical durability increased to 97.20 ± 2.50% and 97.35 ± 5.50% with cassava starch and used engine oil, respectively, although both mean values remained slightly below the selected 97.5% reference benchmark. Accordingly, 260–300 °C is proposed as a promising development window under the investigated conditions rather than a validated process optimum. Because vibration intensity, process-gas flow, oxygen concentration, reactor energy consumption, combustion emissions, and contaminant behavior were not fully instrumented, the study does not claim a quantified reactor-performance advantage or demonstrated environmental superiority. Cassava starch is therefore the preferable tested binder when a bio-based formulation and high pellet density are prioritized.