Groundwater is the main source of life in Jhunjhunu district of Rajasthan state, especially in rural and semi-urban areas. The main objective of this study is to do a scientific, comparative and systematic analysis of the quality of groundwater available in different parts of Jhunjhunu district and evaluate it through Water Quality Index (WQI). This research work is important from the point of view that this region is facing continuous decline in water quality due to climate change, uncontrolled exploitation, and mineral and anthropogenic reasons. In this study, a total of 30 water samples were collected from different blocks of Jhunjhunu district (such as Mandawa, Nawalgarh, Surajgarh, Udaipurwati etc.). These samples were analyzed as per the guidelines of Bureau of Indian Standards (BIS:10500) for major physico-chemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), hardness, alkalinity, calcium, magnesium, nitrate, chloride, fluoride etc. Based on the data obtained, the Water Quality Index (WQI) was calculated using the Weighted Arithmetic Water Quality Index method. The WQI analysis concluded that water quality in some areas such as Nawalgarh and Mandawa falls in the very poor category, while in some areas of Surajgarh and Khetri, water was found to be in the moderate or acceptable category. This shows that water quality in the district varies greatly from place to place. This study can not only prove useful in formulating local water management plans, but is also helpful in increasing awareness among the general public about water conservation, sanitation and sustainable development. Finally, it is concluded that policy intervention, public participation and regular monitoring are necessary to improve water quality in Jhunjhunu district.