The frequent occurrence of anaerobic digester process instability and system failure poses significant challenges to the widespread adoption and success of biogas technology. This study investigated the effects of different parameters on biogas production using a biofilm carrier in the anaerobic digestion of compressed water hyacinth juice. The batch AD experiment coupled with BET and FTIR analysis of biofilm carriers has revealed that a specific combination of (particle size of 1.69mm, and activation with NaOH at 578°C carbonization temperature) produced the highest cumulative biogas and methane yield with good fitting to a modified gompertaz model. The best biofilm carrier from the batch study was applied in the UASB reactor operated at three different HRTs of 2, 4, and 6 days at a neutral pH range and mesophilic temperature 370c. The cumulative biogas production in the UASB reactor within 67 days of operation time was 250mLg-1VS-1, 412mLg-1VS-1, and 324mL g-1VS-1 for control, activated biochar and biochar treated digesters respectively. Activated biochar and biochar-treated digesters have been found to significantly increase biogas production, by up to 39.1% and 22.8% respectively compared to the control. The study found that the lowest HRT of 2 days resulted in the highest biogas and methane production. The average steady-state biogas production levels at HRT 2 days were 200mL/day, 275 mL/day, and 340 mL/day for the control, biochar, and activated biochar-amended digester respectively. Compared to the control, the biochar and activated biochar amended digesters showed significant enhancements in cumulative methane production with increases of 31.6% and 47.8% respectively. The average COD removal efficiency of 65.5%, 72.7%, and 80.23% was achieved in control, biochar, and activated biochar amended AD respectively. It was revealed that the textural and morphological changes of the biochar during activation played a significant role in facilitating microbial attachment and promoting biofilm formation which leads to higher biogas and methane production. Keywords: Anaerobic digestion, Biogas, Water hyacinth, Biofilm carriers, UASB