Global crop production must balance better yields while reducing energy use and greenhouse gas (GHG) emissions, particularly from irrigation and nitrogen (N) fertilizers. This study assessed deficit irrigation (DI) (100 %, 70 %, and 40 % of crop evapotranspiration: DI0, DI30, DI60), N rates (40, 80, 120 kg ha(-1): N-40, N-80, N-120), and plant bio-regulators (PBRs: no PBR, thiourea @ 500 ppm, salicylic acid @ 0.5 mM) on energy use, GHG emissions, productivity, and profitability of Indian mustard in India's arid region. Total energy input ranged from 13,928 to 25,940 MJ ha(-1), with electricity used for irrigation (36-64 %) and fertilizers (14-41 %) being the major contributors. Moderate deficit irrigation (DI30) saved energy (14 %), irrigation water (25 %), and lowered yield-scaled global warming potential (GWP) by 14 %, with only a 2 % yield reduction compared to DI0. Higher N rates (N-120) increased yields (45-81 %) and profits (146-252 %) but raised energy consumption and GWP. PBRs improved yields (6-8 %) and reduced yield-scaled GWP (8-10 %) with minimal effect on energy use. DI30 with 120 kg N ha(-1) and 500 ppm thiourea identified as the optimal strategy for balancing yield, profits, resource use and environmental impacts for mustard production in arid, water-scarce regions.