A considerable amount of research was conducted to develop and validate instruments for measuring ethical behavior concerning using information and communication technologies (ICTs). However, there is a lack of measurement scales that measure the ICT unethical behavior among undergraduate students. Therefore, this study develops and validates a new research instrument called the ICT unethical behavior scale. This research examines the configural, metric, scalar, factorial, and error invariance across gender based on two surveys collected by 1827 (study 1) and 1821 (study 2) undergraduate students at six universities in Oman. The structural equation modeling (SEM) and the independent samples t-test were employed. The results indicate that the 18-item developed scale is a reliable and valid tool for assessing ICT unethical behavior among undergraduate students. The scale depicts good configural, metric, and scalar invariances across gender groups. Although the practical strength of the gender difference is minor, female undergraduates reported significantly higher ethical behavior than males. The implications of the study posit a postmodern approach to scrutinizing gender differences in ICT unethical behavior. By substantiating the measurement invariance of an ICT unethical behavior across gender groups, the findings refute the conventional biased view that one gender is more or less ethical than the other.