Food safety is an important issue in the school environment, especially by food handlers responsible for providing lunches to students, who are vulnerable to foodborne diseases. This cross-sectional study assessed the demographic characteristics of food handlers, including food safety-related knowledge and behaviour, and their impact on Escherichia coli bacterial contamination on their hands. Data were collected from 88 foodservice workers in 6 selected schools from a structured questionnaire and a hand swab test. The results showed that 39.8% of the food handlers had good knowledge and 38.6% implemented good food safety practices. These findings are significant, considering that 10.2% of food handlers tested positive for Escherichia coli, which can be fatal to the health of vulnerable students. Further statistical analyses identified a significant relationship between food handler behaviour and Escherichia coli contamination (p = 0.031), although no significant relationship with knowledge level was determined (p = 0.135). This study underscores the importance of food safety training for non-certified food handlers in internal school catering services. These results also provide a knowledge basis for policymakers and schools regarding taking immediate preventive measures to maintain the health and safety of students.