Background: To help redress the global bias of intellectual disability research drawing on high‐income countries, previous studies have used data from UNICEF's Early Child Development Index (ECDI) to create an indicator of Significant Cognitive Delay (SCD) in young children. Recently, UNICEF have replaced the ECDI with an updated 20‐item version; the ECDI2030. Our aim was to investigate the utility of using ECDI2030 data to provide a more robust measure of SCD. Method: We conducted secondary analysis of ECDI2030 data on 92 506 2–4‐year‐old children from 23 nationally representative surveys undertaken primarily in the world's poorer countries. Results: The 11 learning items of the ECDI2030 showed good internal consistency overall and in each of the participating countries. Using age‐specific cut‐points for SCD generated from 20 013 children in nine countries with high Human Development Index (HDI) scores produced country‐level estimates of the prevalence of SCD that ranged from 1.1% to 34.1%. These prevalence estimates showed a strong relationship with both country HDI score and national wealth. Increased within country risk of SCD was independently associated with male gender, lower relative household wealth, lower level of maternal education and non‐enrolment in early childhood educational programmes. Comparison with SCD based on the older ECDI indicated that the two versions correlated very highly, although the newer version produced slightly higher prevalence estimates than the previous version. Conclusion: The ECDI2030 is being used in Round 7 of UNICEF's Multiple Indicator Cluster Surveys which are currently underway in 46 countries and in a growing number of USAID funded Demographic Health Surveys. Individual‐level data from surveys are freely available to researchers. As data from these surveys begin to be released, they will provide a highly cost‐efficient way to redress the current bias in intellectual and developmental disabilities research toward high‐income countries and to understand the of children at risk of intellectual disability or global developmental delay in the world's poorer countries.