<p>Kaptai Lake, the largest artificial lake in Southeast Asia, holds global ecological significance due to its rich biodiversity. Although created for hydroelectric power generation, it is now home to about 74 fish species and other aquatic organisms that support small-scale fisheries and contribute to the socioeconomic development of local communities. Therefore, the study focuses on assessing the spatiotemporal dynamics of the water and sediment characteristics of Kaptai Lake to provide baseline information for its sustainable management. Twelve months of sampling was done at four stations of the lake. Water parameters such as water temperature (WT), dissolved oxygen (DO), pH, total dissolved solids (TDS), alkalinity, hardness, carbon dioxide (CO₂) and ammonia, and soil parameters such as organic carbon and organic matter were determined. Statistical analysis showed that alkalinity and CO₂ varied among the sampling stations (<i>p</i> &lt; 0.05), while WT, DO, TDS, alkalinity, organic carbon, and organic matter showed significant variation across the sampling season (<i>p</i> &lt; 0.05). Seasonal variation in Kaptai Lake was more noticeable than spatial variation, as the lake’s uniformity limited spatial differences. However, water and sediment characteristics varied significantly over time. Multivariate analyses, such as cluster analysis (CA) and principal component analysis (PCA), revealed that alkalinity, TDS, and hardness influence variability while grouping stations and seasons. This research generated baseline information on the spatiotemporal dynamics of Kaptai Lake, offering critical insights for its sustainable management.</p>