Continuous assessment of butterfly diversity in metropolitan areas is necessary for keeping track of the effect of urbanization on biodiversity. Apart from being charismatic species, attractive and colourful butterflies serve different ecosystem functions and services and thus require monitoring and conservation. In the present study, butterfly diversity was assessed as a part of continuing studies on the butterflies of Kolkata, India, to get an understanding about the present status of this group. A random sampling of three sites in Kolkata metropolis confirmed the presence of 48 butterfly species, dominated by Nymphalidae (37.5%), over Lycaenidae (22.9%), Pieridae (16.7%), Papilionidae (12.5%) and Hesperiidae (10.4%). The relative abundance of butterflies varied with the month and Family. During the yearlong study, it was observed that the 48 butterfly species recorded were associated with 40 different angiosperm plant species. The species composition and abundance of butterflies differed a little from previous studies. Variations in habitat conditions and sample sizes may be the reasons for the observed variation in the structure of the butterfly-plant community. The dependency of butterflies on different plant species was measured by network analysis. The various network indices reflected the nested pattern of the butterfly-plant community and the lower H2′ value (0.4) suggested the presence of generalized species of butterflies within this group. In addition, modularity evaluation revealed some close butterfly-plant species linkages and the presence of specialized butterfly species. In an urban area, an estimate of the relative strength of butterfly-plant interactions can be used to identify the specific plant species supporting butterfly populations. Keeping this view, in addition to diversity analysis, butterfly–plant interactions were also re-evaluated for their contribution to habitat restoration and enhancement of the population of desired butterfly species in urban areas such as Kolkata, India.