The study aimed to assess (i) the effects of Prosopis juliflora invasion on the diversity of plant species, and floristic composition at Awash Fentale and the Amibara districts of the Afar region and (ii) the effects of P. juliflora invasion on the regeneration potential of native woody species. Sample collection was performed in habitats of P. juliflora thicket, P. juliflora mixed with native species stands, non-invaded woodlands, and open grazing lands. A stratified random sampling technique was used for data collection. Among species of plants, the highest proportion of species, 87 (27.4%), was recorded under non-invaded woodlands, but the lowest proportion of species, 70 (22%), was recorded under open grazing lands. The invasion level of P. juliflora caused significantly reduced Shannon diversity index. The mean values of Shannon diversity index and species richness under P. juliflora mixed with native species (H’=2.22, R=14) and non-invaded woodlands (H’=2.23, R=13) were significantly higher than P. juliflora thicket (H’=1.96, R=12) and open grazing lands (H’=1.84, R=10). In this study, 102 trees ha-1native woody species were recorded under P. juliflora thicket, but 1252 trees ha-1native species were recorded under non-invaded woodlands. If the present effects of the invasion of P. juliflora on native species diversity were to continue coupled with a drier climate, plant diversity of the Afar flora region will be highly affected. As a result the ecosystem services will be under threat. Thus, the participation of all stakeholders and multidisciplinary research approaches should be designed for the management of invaded rangelands to reverse the situation.