To enhance efforts against plagiarism, a deeper understanding of its various aspects is essential. This cross-sectional questionnaire study assessed the knowledge, attitudes, subjective norms, and self-reported plagiarism practices among health researchers in Egypt and Lebanon. A validated questionnaire was distributed to postgraduate students and faculty members across 15 universities through personal emails and health researcher-specific social media platforms. Out of 283 respondents, the mean knowledge score was 14.8 ± 3.7 out of a possible 27.0, indicating moderate knowledge of plagiarism. Attitudes toward plagiarism were moderately permissive, with an average score of 62.2 ± 10.9, out of a maximum of 90.0. Subjective norms received a moderate score of 33.6 ± 6.7, where a favorable score should be low (10–23) suggesting that participants perceive society as disapproving of plagiarism and believe its prevalence is low. The mean self-reported Plagiarism Severity Score (PSS) was 4.1 ± 3.6, reflecting a low level of self-reported plagiarism, with a maximum possible score of 18. Multivariable analysis revealed a negative correlation between subjective norms and the PSS (β = −0.194, CI [−0.196: −0.010]). This finding is counterintuitive, as one would typically expect that a lower subjective norms score (indicating stronger disapproval of plagiarism), would correlate with fewer acts of plagiarism. One possible explanation for this result is the presence of negative perceptions of organizational justice—such as feelings of being unfairly treated—which might lead to higher rates of self-reported research misconduct. We recommend that universities in the Arab Middle East region develop research ethics training programs that include responsible conduct in research. However, it is essential for academic leaders to assess and address the research integrity climate within their institutions, as organizational injustice could undermine the effectiveness of these educational efforts.