Objective: Oral hygiene knowledge is considered an essential prerequisite to any community member. Dental caries is highly prevalent among children and persists to be a significant public health problem. Hence, this study was conducted to assess the knowledge, attitude, and practices of oral hygiene care among 12-year-old children in Chengalpattu district, India. Materials and methods: A cross-sectional descriptive study was conducted among 228 school children in Thirukalukundram Taluk, Chengalpattu district. The questionnaire has demographic data and five questions on knowledge toward oral hygiene maintenance, five questions on students’ attitude toward oral hygiene maintenance, and five questions toward oral hygiene practices. Data obtained were statistically analyzed and results have been obtained. Results: Almost 57.3% students were aware that bleeding gums indicate gum disease. Most of the participants (61.6%) knew the symptoms of dental caries; 98.1% students used tooth paste and brush for brushing; 74.4% students never visit a dentist even on discomfort, 22.3% students visit a dentist on discomfort, 2.4% students visit a dentist once a year, 0.9% students visit dentist once in 6 months; 77.3% of students were aware that brushing before bed is mandatory. Conclusion: Children had good knowledge on oral hygiene practices; however, few of them exhibited a negative attitude toward practice of recommended oral hygiene measures which can be addressed in future by motivational programs on oral hygiene.