Nitrate as a nutrient becomes a part of stormwater runoff originating from point and non-point sources such as fertilizers in agricultural fields, domestic wastewater, and livestock. This nutrient ultimately gets discharged into surface waterbodies. The removal of nitrate (NO3−-N) as nutrient using adsorption is an economically viable way to augment conventional treatment methods. The current study focuses on removal of nitrate from aqueous medium using bamboo-biochar provided with and without surface charge modifications. The biochar was produced in laboratory by slow pyrolysis of bamboo at 500 °C. Due to the presence of electro-negative surface charge over biochar surface, the affinity towards NO3−-N removal is low as a result of electrostatic repulsion between both the species. Thus, the prepared biochar was modified with 5% FeCl3 to increase metal oxides over biochar surface. This biochar was used to remove the nitrate present in stormwater runoff originating from various land uses based on major associated activities, namely commercial, industrial, institutional, and roads of urban area. The biochar was able to remove 45%, 46%, 65%, and 56% nitrate, respectively, from land use area commercial, industrial, institutional, and roads. The biochar modified with metal oxides have a relatively higher nitrate removal capacity than unmodified biochar due to change in surface charge to electro-positive. The Langmuir adsorption isotherm studies indicated monolayer adsorption while, Freundlich indicated multi-layered and heterogenous sites for adsorption of nitrate.