This study has determined the level of teachers' preparation for children with special needs in Southwestern Nigeria, and investigated the influence of teachers’ preparation on the Social Studies academic performance of children with special needs in the study region. These were with the main aim of investigating the influence of teacher preparation on the Social Studies academic performance of children with special needs in Southwestern Nigeria. The population comprised children with different special needs categories which include Auditory Impairment (AI), Visual Impairment (VI), Emotional Disturbance (ED), as well as children with Learning Disability (LD). The sample consisted of intact classes of pupils in Primary One to Three. The multistage sampling procedure was used to select samples for the study. Three states were selected from six states in Southwestern Nigeria using the purposive sampling technique. These states were selected based on the availability of special needs schools. In the three selected states, purposive sampling technique was used to select three public special schools making a total of nine special schools in all. Two research instruments were used to collect data for the study. It was found that the study has shown that the level of teachers' preparation in teaching children with special needs in South Western Nigeria was moderate (48.0%). In the same vein, there was a significant influence on the academic performance of children with special needs in Social Studies in Southwestern Nigeria (p=0.05). It can be concluded that teachers’ preparation has a significant influence on the academic performance of children with special needs in Social Studies in Southwestern Nigeria.