To prevent environmental pollution, promote ecological restoration and impart production sustainability in biomass crops, optimization of mineral fertilization regimes is strategically required under changing climatic scenarios. There exist research gaps regarding optimal use of nitrogen (N), phosphorous (P) and potassium (K) fertilizers for the fertilizer-responsive cultivars of forage legumes like cowpea under decreasing soil fertility in semi-arid regions. Therefore, a multi-year field experiment was executed to study yield attributes, green and dry matter yields along with nutritional quality attributes of forage cowpea (cv. Rawan-2003). The treatments were comprised of different N-P-K levels viz. F0= (0-0-0), F1= (150-0-0 kg ha-1), F2= (150-100-0 kg ha-1) and F3= (150-100-100 kg ha-1). The findings revealed that F3 fertilization regime surpassed rest of treatments by recording the maximum plant population, plant height, leaf area index, plants fresh and dry weights, which led to the highest green forage yield (73% and 5.8% higher than control and following treatment of F2, respectively). For dry matter yield, all fertilization regimes performed better than control, however those were statistically at par to each other. Moreover, F3 treatment exhibited 4.4% and 1.6% higher crude protein and ether extractable fat respectively, compared to the following treatment of F2 treatment that remained at par to F3 for total ash content. Contrastingly, the control treatment remained superior by giving the minimum crude fiber content which could be attributed to dwarf plants produced in the absence of fertilizers because stem length tends to contribute the major portion of fiber content in cowpea. Thus, 150-100-100 kg ha-1 N-P-K might be recommended to cowpea growers for boosting biomass productivity and nutritional quality, however further field investigations need to assess the impact of these fertilization regimes on biological N fixation process and solar radiation capture by cowpea plants under irrigated and dry semi-arid conditions.