In freshwater environments, salinity is a significant environmental stressor that has an impact on aquatic plant development and survival. Elevated salinity levels, frequently originating from natural processes or human actions, can lead to diminished plant growth, poor photosynthesis, and even plant mortality. Hence, the present study aimed to analyze the salinity tolerance level of the macrophyte Egeria densa, assess the biochar induced growth of E. densa in different saline condition (5 and 10 ppt) in addition of biochar (15 and 30 gm). The increased interest in biochar as an environmentally friendly and sustainable amendment to improve plant resilience in harsh environmental circumstances is the driving force for this work. The study analyzed different water quality parameters, shoot weight gain rate (SWR), shoot growth rate (SGR), root growth rate (RGR), total chlorophyll, carotenoids, and availability of florescence dissolved organic matter (fDOM). Experimental analysis was conducted in a setup at a laboratory scale for 10 days. Slight difference was observed in water quality parameters (pH, electrical conductivity, total dissolved solids and dissolved oxygen) and the identified salinity threshold level of E. densa were 5 ppt. SWR (0.014 gm/day), SGR (0.14 cm/day), RGR (0.015 cm/day), total chlorophyll (0.34 mg/g fresh weight) and carotenoids (0.16 mg/g fresh weight) concentration substantially increased with the application of 5% biochar in the 5 ppt saline water. Fulvic acid, p-Cresol like substance, and Protein-like extracellular polymeric substance (EPS), and anthracene-like peaks were found in the fDOM. According to the study, biochar increased plant growth at 5 ppt salinity, however neither Egeria densa nor biochar reduced the salinity of the water. Biochar aided E. densa in adapting to salt stress by increasing shoot length, root development, and chlorophyll levels.