Considering the very extensive destruction of natural resources, particularly with respect to the rangelands, the role of ranchers in conserving these resources is critical. Although this issue is important, insufficient attention has been paid to ranchers’ intention to conserve rangelands and understand their formation process. To narrow the research gap, this research established a theoretical research model by adding moral norms into the Theory of Planned Behavior (TPB) to explore factors affecting ranchers’ intentions to conserve rangelands. Data were collected through questionnaire from a sample of 120 Iranian ranchers. The results of structural equation modeling indicated that all three of the TPB’s psychological variables, i.e., attitude towards conserving rangelands, subjective norms and perceived behavioral control were related significantly to ranchers’ intentions to conserve rangelands. Further, subjective norms had a positive and significant relation to attitude towards conserving rangelands, perceived behavioral control, and moral norms. In addition, moral norms were related indirectly and significantly to ranchers’ intentions to conserve rangelands via their attitude towards doing so. This research is useful for understanding ranchers’ intentions to conserve rangelands and also valuable for encouraging ranchers to conserve rangelands.