Autism is a spectrum of neurodevelopmental disorders exhibited in early childhood with variable manifestations as children grow up. Therefore, teachers need to understand the condition in order to deliver apt educational services to autistic children. However, the level of awareness of the condition is poorly understood among pre-primary school teachers. This study,therefore, analyzed the understanding of the spectrum condition of autism among pre-primary school teachers in western Kenya. A descriptive cross-sectional study design was employed to assess the understanding of the spectrum condition of autism among 321 lower school teachers of Kisumu Central sub-county in western Kenya. The study participants were selected using purposive sampling, and primary data was collected using semi-structured questionnaires and a Key Informant interview guide. The quantitative data were analyzed using SPSS version 20. However, the qualitative data were analyzed thematically. The response rate was 76.9% with 16.8% (41) males and 83.2% (203) females. A total of 41.5% (n=110) of the teachers had never heard of autism. Of all the teachers who had heard of autism, 100% (7) were from special needs schools, and 64.4% (67) and 45.1% (60) were from public and private schools, respectively. About 78.8% (105) of teachers perceived autism as a neurodevelopmental disability and academically challenged children, 15% (20) as a psychiatric illness similar to madness, 4.5% (6) as spiritual affliction/demon-possessed children and 1.5% (2) as parental neglected children. This study shows that lower school teachers have an inadequate understanding of the spectrum condition of autism, and this limits service delivery. This study, therefore, recommends special training for pre-primary school teachers to cover the spectrum condition of autism.