It is crucial to comprehend climate variability, trends, and prediction to improve basin-wide planning and management of water resources. The water reserves in Kerala’s Alappuzha district are particularly vulnerable to climate change; therefore, the current study examined changes in land use and land cover (LULC) during 20 years. An array of changes in land use and land cover (LULC) were witnessed on the Earth’s surface. LULC forms depend on human practice in terms of socio-economic development and nature over space and time. Land use/land cover changes in the Alappuzha district, Kerala, during the period 2001–2021 were evaluated using satellite data and USGS (United States Geological Survey) Topo maps. The LULC aspects are categorized into five classes: waterbodies, rivers and ponds, agricultural area, barren land, and built-up area. Through ArcGIS analysis, it was discovered that gradual changes in agricultural land areas and reduction in area size (in 2001, area size comprised 59%; in 2011, 61%; and in 2021, 56%) were followed by a gradual increase in built-up areas, especially after 2011, doubling the percentage of built-up land. In recent years, the LULC map showed a little deviation in the forestland areas and a gradual reduction in waterbodies, but tremendous changes in the paddy land cultivation had been observed. The results propose fundamental details on the LULC changes in the Alappuzha district, which will be used for developing regional strategies for better land planning and utilization.