Almost half of all children with a disability do not receive a disability grant while 38% are not in school, according to the United Nations Children's Fund (Unicef).
The number of children with disabilities is estimated at almost 240 million, or one in 10 children globally.
In Thailand nearly 140,000 children live with some form of disability, according to a 2017 survey by the National Statistical Office (NSO), with technical support from Unicef.
Most of them live in poor households. About 38% are out of school; 27% do not have access to health promotion services and 4% lack access to medical treatment.
"Children with disabilities are among the most vulnerable groups in every society and have the fewest opportunities in every aspect of life," said Kyungsun Kim, Unicef's representative for Thailand.
"Facing stigma and discrimination, they are less likely to attend school, access health services or have their voices heard. Their disabilities also put them at a higher risk of abuse, neglect and exploitation. This must change because no child should be left behind."
Unicef is calling on the government and society at large to provide equal opportunities for children and persons with disabilities, eliminate stigma and discrimination, and ensure they have equal treatment and access to inclusive and quality health and education services as well as assistive technologies.
In Thailand, Unicef is working with the NSO and the Department of Empowerment of Persons with Disabilities to promote quality data on children with disabilities and ensure that children and persons with disabilities have equal access to inclusive and quality services as well as the disability grant they are entitled to, Mr Kim said.