Aim: Amelioration effect of soil amendment on growth and yield of Vigna unguiculata L. grown in acidic and alkaline soils. Study Design: The study was conducted in a randomized complete block design with five replicates. Place and Duration of Study: Department of Botany, University of Calabar, Nigeria, between May and September, 2017. Methodology: Composite soils from two locations Akamkpa (pH 4.0) and Odukpani (pH 9.0) were collected, mixed thoroughly with organic manure (OM) and agricultural lime (AL) singly and in combination, allowed to stay three weeks for proper blending before V. unguiculata seeds were sown. On seedlings germination, amelioration effect of soil amendment on growth and yield of cowpea grown in acidic and alkaline soils was studied at different periods of growth. Results: Results revealed significant (P=0.05) increase in leaf area, plant height, number of leaves, leaf fresh and leaf dry weight, relative growth rate, net assimilation rate and leaf area ratio of V. unguiculata grown in acidic and alkaline soils treated with OM and AL. Pod length, number of pods plant-1, number of seeds pod-1, number of seeds plant-1, weight of 100 seeds increased significantly. Organic manure used singly and in combination was more effective in ameliorating soil pH effect than AL. Vigna unguiculata performed better in treated and untreated alkaline than in acidic soils. Least plant height for V. unguiculata grown in untreated alkaline soil at 12 weeks after sowing WAS was 60.22±0.16a cm and highest 119.63E2±.35g cm for plants grown in soil treated with AL1+OM1. Least number of seeds plant-1 for plants grown in untreated acidic soil at 12 WAS was 90.60±0.02a and the highest 139.18E2±0.02e for plants grown in soil treated with AL1+OM1. Conclusion: An improvement in growth and seed yield of V. unguiculata grown in acidic and alkaline soils is feasible through the use of organic manure and agricultural lime.