Recognised as the phenomena of worldwide occurrence, urban sprawl and accompanied chaotic built-up growth in and around existing urban clusters, have been found to have irreversible environmental, social and economic externalities, many of which are negative in nature. Though urban sprawl has emerged as a significant dimension of urbanisation throughout the world, it is imperative to be cognizant of the ways in which urban areas spatially grow since they differ in accordance with specific norms and regulations. To understand the spatio-temporal trajectory of urban sprawl of a city, therefore, it is essential to first understand the existing nature of land utilisation and its dynamics. Accordingly, the present study endeavours to understand and detect the territorial transformations encompassing Siliguri, the third largest city of West Bengal, India, over a period of two decades (2001–2021), through an integrated remote sensing-GIS approach. The research is grounded on quantitative methods like ‘Urban Expansion Intensity Index’ (UEII), ‘Landscape Expansion Index’ (LEI) and ‘Shannon’s entropy’ to quantify and address the non-linear pattern of urban spatial growth in and around Siliguri city. The results of UEII indicate that the growth intensity of built-up areas in Siliguri urban agglomeration has increased over the time, whereas Shannon’s entropy portrays a picture of increasing magnitude of built-up expansion in the study area. Finally, the LEI depicts an extraordinary dominance of edge-expansion as the principal mode of urban sprawl around Siliguri, as well as a growing number of new urban patches coming out over the agricultural tracts without any direct spatial association with pre-existing urban patches. The results of this study are expected to furnish empirical insights into the spatial pattern of urban growth, encompassing Siliguri, which may assist policymakers in planning for a sustainable pattern of urbanisation for the city and its surrounding region.