This study was designed to assess the impact of Islam on the cultural practices of Nupe people. The study was therefore, focused on some cultural practices in Nupe-Land in relation to the cultural behaviours of Nupe people. It was observed that the Islamic literature of Nupe people have not coverall the field of their cultural practices especially, the aspect of belief and its relation to some cultural norms like Gboya (masquerade) and Ndaduma (father Niger). It was also observed that there are some prints of cultural practices observed along with Islamic teachings, e.g. belief in veneration of Jinn (Jennu-Nupe:demon), spirits and practice of divination. Another problem observed was the cultural practice of Nupe Muslim women marrying non-Muslims. As a result, the study was intended to determine the impact of Islam on the cultural practices of Nupe people. It was further aimed at positioning the stand of Islam on some Nupe cultural practices against their lawfulness and unlawfulness, and draw up recommendations that will ensure effectiveness in carrying out their obligations or duties as Muslims. Survey design method was adapted and applied for this study. Also, a proportional stratified sampling method was used to secure a uniform sampling fraction (S.F) from stratum. As a result, some Nupe urban and rural settlements were sampled from three states of Nigerian Federation: Niger, Kwara and Kogi. A questionnaire was designed and administered to 1,066 respondents randomly selected from the urban and rural communities of the above named states. Five (5) null hypothesis and five (5) research questions were formulated and analyzed. Forty two (42) items were generated in the questionnaire using summative rating scale of 1 - 3 response scale. The pie chart was used to determine the level of significance and the relationship between variables at 100 %. The result revealed that Islam has made a significant impact on the cultural practices of Nupe people in many facets of their life and instilled in them the zeal to improve their general religious affairs. The result further indicated that there is significance difference between Islam and the cultural practices of Nupe people. However, the research findings showed that there is lack of sufficient Knowledge of Tauhid(Unity of God). Also, there is lack of sufficient Knowledge of Islamic teachings about commercial laws and regulations. The findings further includes the reluctance on the part of some Nupe Muslims to seek or search for authentic information about Islamic teachings on certain issues such as Istikharah(means of seeking solution from God regarding what one intends to do).