Humans and nature have a complicated connection when it comes to ecosystem services. If these interactions remain unmodified, they are self-sustaining. However, because of increased urbanization, changes in land use land cover (LULC), and human activities, these ecological services (ES) are under great strain. This research looked at changes in land use and land cover in the Mangaluru urban agglomeration, a coastal area of Karnataka (LULC). The object-based image analysis (OBIA) strategy was adopted to characterize the spatiotemporal variations in LULC during five decades, 1980, 1990, 2000, 2010, and 2022. The fundamental purpose of this study is to get knowledge about various LULC classes. Using the OBIA approach, the research area is separated into five classes: built-up area, water body, forest area, agricultural land, and barren land. The accuracy of categorization is evaluated using photos from Google Earth, SoI Topo maps, and on-the-ground confirmation. We found that between 1980 and 2022, the area used for agriculture declined, the forest area expanded, the area used for structures increased substantially, the area of water bodies remained stable, and wasteland/shrubland dropped significantly. This lays the way for understanding the key drivers of changes in LULC, which are covered in the study. The correctness assessment findings show that the LULC modifications mentioned in this study are truly valid and relevant to future usage. Decision-makers may find the study's conclusions useful in selecting the best course of action in the future if the city is to be expanded. This research also shows the use of GIS and remote sensing (RS) in LULC applications, notably in coastal areas.