The study aimed to investigate the prevalence and associated factors of dental caries on primary teeth and to evaluate the cariogenic bacteria in dental plaque and saliva among Myanmar schoolchildren. A cross-sectional study was undertaken among 264 schoolchildren from three primary schools in the urban area of Yangon city in 2019. Clinical oral examinations, caries risk tests, and questionnaire surveys were conducted. Overall caries prevalence was 84.1% with a mean decayed, missing, filled primary teeth (dmft) count of 5.84 ± 4.57. Children’s caries experience and debris scores were significantly associated with their bacteria score level. Father’s occupation was significantly associated with caries prevalence ( P = .024) and dmft ( P = .021). Father’s occupation, snack types, habit of eating sweet food combinations, drink types, and debris score were five significant predictors of dental caries in our study. Dental caries is currently a public health problem among Myanmar children. Caries experience and oral hygiene status were strongly influenced by cariogenic bacteria.