BACKGROUND: The majority of children with sensory impairments live in low- and middle-income countries. More studies of hearing and vision impairment prevalence are needed, in order to generate more accurate estimates of trends in sensory impairments. This study aimed to estimate the prevalence and describe the characteristics of hearing and vision loss among preschool children (4-7 years) in an underserved South African community following community-based mobile health (mHealth) supported hearing and vision services. METHODS: A screening program of sensory impairments was undertaken of children attending preschools in the communities of Khayelitsha and Mitchell's Plain, Cape Town, from September 2017 until June 2019. Hearing and vision screening were done by trained community health workers using mHealth technology. Children who failed hearing and vision screening were seen for follow-up assessments at their preschools. Follow-up assessments were conducted using smartphones that host point-of-care validated and calibrated hearing and vision testing applications (hearTest app, hearX Group, South Africa and PeekAcuity app, Peek Vision, United Kingdom). Descriptive statistical analysis and logistic regression analysis were conducted after extracting data from a secure cloud-based server (mHealth Studio, hearX Group) to Microsoft Excel (2016). RESULTS: A total of 10,390 children were screened at 298 preschools over 22 months. Of the children screened, 5.6 and 4.4% of children failed hearing and vision screening respectively. Community-based follow-up hearing tests were done at the preschools on 88.5% (514) of children of whom 240 children (54.2% female) presented with hearing loss. A preschool-based follow-up vision test was done on 400 children (88.1%). A total of 232 children (46.1% female) had a vision impairment, and a further 32 children passed the test but had obvious signs of ocular morbidity. Logistic regression analysis found that age was a significant predictor of vision loss (p < 0.05), but not for hearing loss (p = 0.06). Gender was not a significant predictor of hearing (p = 0.22) or vision loss (p = 0.20). CONCLUSIONS: Hearing loss is prevalent in at least 22 per 1000 and vision loss in at least 23 per 1000 preschool children in an underserved South African community. Timely identification of sensory losses can be facilitated through community-based hearing and vision services supported by mHealth technology.