Diarrheal disorders significantly affect child morbidity and mortality, particularly in fishing communities. This study assessed prevalence and risk factors among under-five children using Social Cognitive Theory. A mixed-methods approach surveyed 155 households in Karaikal, India, including environmental surveillance and focus group discussions. Diarrhea prevalence was 30.3%. Key behavioral and environmental risks included lack of awareness, uncovered cooked food, poor sanitation, and chemical/bacterial contamination of water and food. Interventions such as handwashing promotion, sanitation improvements, and healthcare access enhancement were suggested to guide context-specific behavior change communication.