Floristic diversity of Khagrachari Sadar of Khagrachari district, within Chittagong Hill Tracts of Bangladesh, has been investigated. A territory's vegetation type and diversity provide insight into the overall resources, their usage structures, and conservation status that are crucial to developing conservation plans and regulations. This analysis helps to portray the overall scenario of a region's plant biomass/vegetation diversity exquisitely. This study has revealed the occurrence of 369 vascular plant species belonging to 144 genera under 97 families from the study area. Out of these 32 are pteridophytes, 2 are gymnosperms and the rest of 335 are angiosperms. Based on habit distribution, herbs are represented by 150 species followed by shrubs (48), trees (108), climbers (47) and epiphytes by 16 species. Dicotyledonous (Magnoliopsida) group was dominant and represented by 254 species belonging to 73 genera under 62 families, followed by monocotyledonous (Liliopsida) with 81 species under 52 genera and 17 families. Among the dicotyledonous plants, Rubiaceae was found to be the largest family with 24 species, whereas with 17 species Orchidaceae is the largest family in monocotyledonous. It appears that Forested areas are dominated by Melocanna baccifera, with an IVI of 8.00 and have the scanty appearance of two herbs (Spathoglottis plicata, Adiantum flabellaletum) and one tree species (Cycas pectinata). For effective conservation management and sustainable usage of the taxa, the status of occurrence has been determined where 304 species (82.23 percent) are considered as ‘Common’, 61 (16.53 percent) are considered ‘Least Concern’, 2 (0.54%) are considered ‘Vulnerable’ and 2 (0.54%), are considered ‘Critically Endangered’. Several diversity indices, such as Margelef’s richness, Shannon-Winer Index, Pielou’s Evenness, and Simpson’s Index values showed the substantial diversity status of the vascular plant in selected 4 sites. A considerable seasonal fluctuation was evident in the diversity indices at four different research locations where data reflected that the rainy season is more diverse than others.