Social studies is a core subject at the basic education level in Nigeria which has the potentials of inculcating functional knowledge and desirable morals into pupils for effective citizenship participation through peaceful coexistence. However, despite this positive trend, the moral significance of peace education contents of the subject seem not to have been adequately explored. This lacuna justified the need for this study which sought to find out the moral relevance of peace education contents in basic education social studies in Nigerian schools. The study adopted a descriptive survey design with content analysis bias. A sample of 200 social studies teachers undergoing in-service sandwich training were selected through stratified random sampling technique from states across the six geo-political zones of Nigeria. Three research questions guided the study. Similarly, two major instruments namely 10-item questionnaire titled "Teachers' Awareness of the Moral Relevance of Peace Education Contents in Basic Education Social Studies Curriculum" and content analysis of the same social studies curricula published by NERDC, a foremost Nigerian educational regulatory body were used for data collection. Data collected were analyzed with the use of arithmetic percentages. Findings of the study showed that majority of the teachers were not only aware of the moral relevance of peace education contents in basic education social studies curricula but were also of the opinion that the subject could be used to meet the moral and peace education needs of Nigerian pupils for the purpose of inclusion citizenship participation. It was also established that peace and moral education contents were adequately reflected in the basic education social studies curricula. These findings were exhaustively discussed with far-reaching recommendations on how to improve the teaching and learning of moral aspects of peace education contents through the basic education social studies curricula for effective promotion of inclusive citizenship participation in a multi-ethnic and religious society like Nigeria.