BackgroundDevelopmental delay in early childhood can have negative long‐term cognitive and psychiatric sequelae, along with poor academic achievement, so early screening and surveillance are paramount. The aim of this study is to evaluate the impact of screening and surveillance on child developmental delay using the Developmental Surveillance and Promotion Manual (DSPM) and the Thai Early Developmental Assessment for Intervention (TEDA4I) for Thai children aged 0–5 years old.MethodsData were obtained from the routine developmental screening for specific disorders at ages 9, 18, 30, 42 and 60 months conducted using DSPM and TEDA4I from 2013 to 2021. Descriptive statistics were used to analyse the data, and the results are visualised graphically herein.ResultsOnly 56% of the children were screened for child developmental delay using DSPM. The proportion of children screened increased from <1% in 2013 to 90% in 2021. Suspected developmental delay prevalence increased significantly from 3.91% in 2013–2015 to 10.00% in 2016–2018 and 26.48% in 2019–2021. Moreover, of the children with suspected developmental delay who received developmental stimulation within a month, only 87.9% returned for follow‐up visits when they were evaluated again using TEDA4I to ascertain any abnormalities and specific areas of deficit. The overall proportion of children diagnosed with developmental delay was 1.29%. During the pandemic, the proportion of screening tests for child developmental delay at routine vaccination visits and follow‐ups decreased but was still at least 80% in each region.ConclusionsSince 1%–3% of children have suspected developmental delay, early detection is key to treating it as soon as possible. We anticipate that our findings will raise awareness in parents and caregivers about childhood developmental delay and lead to the implementation of early intervention and follow‐up at the rural level in Thailand.