The response of cowpea cv. Cream 7 growth and productivity to potassium fertilization mixed with or without Nano mixture of micronutrients were studied during the summer of 2017 and 2018 seasons at Experimental Farm, Faculty of Agriculture, Zagazig University, Egypt. The experiment aimed to assessed the effect of potassium fertilization levels (0.0, 24, 48 and 72 kg K2O /Fed.), Nano mixture of micronutrients rate (0.0, 0.50, 1.0 and 2.0 g/l) and their interactions on growth, seed yield, macronutrients concentration in shoot and seeds and seed quality of cowpea plants. Source of potassium levels was potassium sulphate (48-52% K2O). The used Nano mixture of micronutrients called “Magrow NanoMix” and it contained Fe (6%), Zn (6%), B (2%), Mn (5%), Cu (1%) and Mo (0.1%). These treatments arranged in a split-plot design with three replicates. The results referred to that fertilizing cowpea plants with potassium at 72 kg K2O /Fed. significantly increased cowpea growth (plant height, branch and leaf numbers per plant as well as branch, leaf and total dry weights/plant), yield components (pod diameter and length, hundred seeds weight, pod number/plant and seed yield/plant and/Fed.) as well as chemical constituents (N, P and K percentages in each leaves and seeds as well as total carbohydrates and protein percentages in seeds, also, total chlorophyll content (SPAD) in cowpea leaves compared with control and the lowest levels under study. The same trend was achieved by using the highest rate of Nano mixture of micronutrients (2 g/l) regarding the increase in most of abovementioned parameters of growth, yield and chemical constituents of cowpea compared with unsprayed plants (control). In general, application of potassium fertilization at 72 kg K2O /Fed. as soil application with Nano-mixture of micronutrients at 2 g/l rate as foliar spray was recorded the best treatments for increasing all cowpea growth and seed yield components as well as N, P, K and carbohydrates percentage in seeds such as compared with control treatment (without using mineral potassium or Nano mixture of micronutrients) in growing season.