Phosphorus is a major limiting nutrient in soils in Ghana. Selection of cowpea varieties that produce good seed yield under low soil phosphorus or those with high phosphorus response efficiency can be a low input approach in solving this problem in Ghana. Two seasons experiments were conducted to evaluate influence of phosphorus (P) fertilizer on growth, nodulation and yield in cowpea. The experiment comprised 12 treatment combinations of 3 cowpea varieties and 4 levels of triple super phosphate (46% P2O5) laid out as a factorial in RCBD with four replications. The cowpea varieties were Asetenapa (IT81D-1951), Asomdwee (IT94K-410-2) and IT89KD-347-57 and levels of P were 0, 20, 40 and 60 kg ha1 P2O5. In the present study, Asomdwee and IT89KD-347-57 recorded the highest and lowest crop growth of 7.88 and 2.02 g m2 day1 at 45 and 60 days after planting, respectively. Growth rate was not consistent with P application; however, application rate of 60 kg ha1 P2O5 yielded the least growth rate in the entire study period except for 60 days after planting in the minor season. Statistically, Asetenapa and Asomdwee recorded similar number, effectiveness and dry weight of nodules and were significantly different from that of IT89KD-347-57 in both seasons. Number, effectiveness and dry weight of nodules in all varieties were directly proportional to rates of P fertilizer application in both seasons. Asomdwee produced the highest seed yield of 1557.00 and 1415.00 kg ha1 for major and minor seasons, respectively. The rate of P fertilizer application was directly proportional to the seed yield in all three cowpea varieties. The highest seed yield of 1682.00 and 1476.00 kg ha1 for major and minor seasons, respectively was produced at 60 kg ha1 P2O5 application. Farmers are, therefore, encouraged to use P fertilizer in cowpea production in Ghana.