The rise in international travel has led to an increase in travel-related infectious diseases. It is predicted that by 2030, the number of international travelers will reach 1.8 billion, with over 250 million people affected globally. This issue also has an economic impact, as the eradication of travel-related infectious diseases leads to a loss of USD 12 billion in tourism. To understand the association between demographic variables and knowledge, attitude, and behaviors related to travel-related infectious diseases, a cross-sectional survey-based study was conducted among 1191 individuals in the metropolitan city of Naples, Italy. Multiple linear regression was performed over three models. The results revealed that knowledge about travel-related infectious diseases was positively associated with age, female gender, non-smoking habits, being single, and higher education attainment. The attitude towards travel-related infectious diseases was positively associated with being female, non-smoking habits, being single, higher education attainment, and a higher level of knowledge. A statistically significant association was observed between behaviors and non-smoking habits and between higher levels of knowledge and attitudes. To address this issue, public health programs could be implemented to improve behaviors in the general population. Overall, this study provides valuable information about the determinants of knowledge, attitude, and behaviors related to travel-related infectious diseases in the general population.