Prevalence of hearing loss in children with autism spectrum disorder (ASD) is uncertain, as it is more challenging to assess hearing function in children with developmental difficulties (DD). We aimed to determine the prevalence and profiles of hearing loss in preschool children with ASD in a Southeast-Asian population who passed newborn hearing screening. A retrospective study of preschool children with DD (ASD, Global Developmental Delay (GDD), and Speech and Language Delay (SLD)) attending the Child Development Unit (CDU) at our hospital was performed. Three hundred and thirty-three children (ASD: n = 129; GDD: n = 110; and SLD: n = 94) underwent hearing assessments. Of these, 10.8% of children (n = 36, comprising 15 with ASD, 12 with GDD and 9 with SLD) had confirmed hearing loss. Hearing loss was predominantly bilateral in children with ASD and GDD; in those with SLD, unilateral and bilateral hearing loss were equally common. Conductive hearing loss occurred as frequently as sensorineural hearing loss in children with ASD and SLD, but was the dominant subtype in those with GDD. Moderate to severe hearing loss (n = 2) was noted only in children with ASD. Children with ASD and GDD required significantly more audiology visits and procedures to obtain conclusive hearing test results, compared to those with SLD. The need to identify hearing loss and monitor for resolution is particularly important in vulnerable populations with communication deficits, such as in those with ASD.