Effect of potassium on growth, yield and quality of mungbean ((Vigna radiata L.) under different irrigation regimes was studied at the Research Farm, Department of Agronomy, University of Agriculture Faisalabad, Pakistan. The field experiment was carried out in May-August 2015 using randomized complete block design with split plot arrangement having three replications with net plot size of 5 m × 1.8 m. Crop variety NIAB-MUNG 2011 was used as test crop. The treatments were comprised of different irrigation regimes at different growth stages; no stress (control), skipping one irrigation at vegetative growth stage, skipping one irrigation at flowering stage, skipping one irrigation at pod formation stage and different doses of potassium viz, 0, 15, 30 and 45 kg ha-1 respectively. To study the economic feasibility of the treatments economic analysis was done. Results showed that number of pods per plant, number of seeds per pod (6.33), 1000-grain weight, seed yield, biological yield and harvest index (31.03), plant height at maturity, number of pod bearing branches (9.00) were statistically significant in treatment I0K3 [(irrigation at vegetative, flowering and pod formation stage) × (one and half recommended dose of potassium (45 kg ha-1)]. Protein contents, leaf area index, leaf area duration, crop growth rate, net assimilation rate and benefit cost ratio (1.80) were statistically significant in the same treatment I0K3 [(irrigation at vegetative, flowering and pod formation stage) x (one and half recommended dose of potassium (45 kg ha-1)]. It was concluded from experiment that better mungbean yield was harvested with more net return when potassium was applied in soil @ 45 kg ha-1 and when there was no water stress.