ADAPTATION to climatic changes by adjusting sowing date and using the optimum planting density can mitigate the negative effects on cowpea productivity. A field experiment was performed during two growing seasons of 2019 and 2020 at the experimental farm of Kafr Al-Hamam Agric. Res. Station, Sharqia Governorate, Egypt. The study aimed to optimize sowing date (31 May, 15 June and 30 June) and planting density (285715, 142860, 95240, 71430 and 57145 plants ha^-1) that perform better in terms of seed and biomass yields as well as seed quality of cowpea under semi-arid conditions. The late cowpea sowing on 30 June appeared to be produced the higher seed yield contributions and yields ha-1, crop and harvest index as well as pure seed. In respect of sowing density, intermediate planting density (95240 plants ha-1) exhibited the higher seed yield components and yields ha-1, crop and harvest index as well as pure seed. Results of interaction indicated that late sowing on 30 June attained the maximum seed yield when intermediate planting density of 95240 plants ha-1 was used. Late sowing under lighter (57145 and 71430 plants ha^-1) and intermediate (95240 plants ha-1) planting densities exhibited the highest pure seed as well as the fewest shriveled and infected seeds. Path coefficient analysis showed that number of pods plant^-1 had exerted positive and high direct effect on seed yield of cowpea (0.385) and 100-seed weight had positive and moderate direct effect on seed yield of cowpea (0.251).