Agriculture plays a vital role in economic development and serves as the source of the primary livelihood for nearly 52% of the country’s population. However, the burgeoning population and uncertainty in climatic phenomena forced the farmers to practice crop diversity, which leads to better financial stability and agricultural sustainability. This aims to examine blockwise crop diversification using data from the district statistical handbook (2010, 2015, and 2020) in a semi-arid district of West Bengal. The crop diversification pattern was analyzed among 12 major crops cultivated in the study area from 2010 to 2020. To fulfil this objective, three renowned crop diversity indices, namely the Herfindahl index (HI), the Gibbs and Martin’s index (GMI), and the Entropy index (EI) were used. The entropy index has used to determinate crop diversity and a multiple linear regression model (MLRM) use to assess how small and marginal farmers’ socio-economic characteristics impact on crop diversity. As part of follow-up coefficient of variation and standard deviation were performed to validate the indices. The study findings reveal a significant variation in crop diversity in 2020 (EI, SD: 0.09) as compared to 2010 (EI, SD: 0.13). Although the overall crop diversity improved in the study area, there is a significant disparity among the CD blocks. Geographically, the northern blocks, namely Sonamukhi, Barjora, Gangajalghati, and so on, have higher crop diversity than their counterparts. Therefore, it is suggested that policymakers and agro-economists design targeted interventions based on location-specific frameworks for farmers to practice cost-effective and sustainable farming.