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Cowpea is a good source of protein, minerals, and vitamins in most developing countries in Africa. However, this legume production is still limited by various biotic and abiotic constraints. Beyond these constraints, the pressure of conventional breeding methods on natural variability exhausted a narrow genetic base of cowpea. Therefore, it is important to explore other ways of broadening the genetic base of the crop. Gamma irradiation is an alternative to increase genetic variability and improve the genetic base of crops. This paper focuses on evaluating the level and structuring of agro-morphological variability induced by gamma radiation among M2 plants of cowpea genotype. So, Tiligre, Moussa local, and KVx396-4-5-2D genotypes were treated with 150 Gy of gamma rays. The M2 generation was then screened for genetic variability. Thus, 38 M1 plants (either 38 x 10 seeds) by genotypes are advanced to the M2 generation based on the plant by line method. Four (04) agro-morphological parameters were used to assess phenotypical variability. Analysis of variance showed a highly significant difference between the families of plants except those of KVx396-4-5-2D for the flowering time. The maximum variability was observed for the number of branches and the length of the peduncles with a very high coefficient of variation. A high broad-sense heritability was recorded for all measured traits (>75%) of Moussa Local; for plant height (81.1%) of KVx396-4-5-2D, for first flower date (80.2%), and peduncles length (78.6%) of Tiligre. Based on phenotypic characters, the principal component analysis (PCA) and the cluster analysis showed variation among genotypes irradiated, and they were grouped into four clusters in KVx-396-4-5-2D, six clusters in Moussa local and Tiligre populations. So, 150 Gy dose of γ-rays was effective to induce variability in morphological and phenological characters within cowpea genotypes.