Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Despite the absence of a cure, early diagnosis and intensive early intervention can improve the outcomes. However, little is known about the median age at ASD diagnosis in Malaysia or the child/family characteristics associated with early diagnosis. Therefore, this study aimed to determine the median age at ASD diagnosis among Malaysian children presenting to the country's largest public tertiary neurodevelopmental center and to investigate the possible demographic, child, and family characteristics associated with an early age at diagnosis. Data were collected between February 2017 and February 2019 from a database maintained by the child development unit of the country's largest publicly funded tertiary hospital, containing data from an ethnically diverse population. Among Malaysian children attending the clinic, the median age at ASD diagnosis was 48 months. Early autism diagnosis (<36 months of age) was associated with increased severity of social communication and interaction impairments, coexisting intellectual impairment, children from high socioeconomic status families, and children who receive joint care from their families and a maid or babysitter. The study findings highlight the socioeconomic inequalities in the country, a lack of parental awareness of early ASD signs, and the presence of cultural influences on the age at diagnosis of ASD.