This study’s major goal is to establish the foundation for the relationship between Immanuel Kant and Jean-Jacques Rousseau, two significant figures of the Enlightenment period, and the notion that Kant owes a lot to Rousseau in ethics, one of the fields where Rousseauist influences are most overt. Although the similarities between perspectives of Rousseau and Kant and Rousseau’s influence on Kant are frequently discussed in the previous scholarship, these similarities and effects are primarily discussed in the contexts of education and politics. This is likely because Rousseau stands out in these two fields rather than ethics. We can say that alternative studies are required in this sense. This resemblance and influence essentially equate to a fundamental human concept that includes ethics, politics, and education because the most fundamental question in all philosophies is “What is a human being?”. In addition, Rousseau, who, as the representative of the Romantic, naturalist movement, resorted to a deeper emotion and conscience instead of reason, and Kant as the most important name of the Enlightenment, stood on the same side in the conflict between the mechanism and determinism in the Enlightenment philosophy and human freedom, responsibility and morality against philosophy, gave priority to practical reason over theoretical reason. This constitutes the justification for such an assertation. In this context, in this study, the effect of Rousseau on Kant’s ethics has been tried to be revealed based on certain concepts of the ethics of both names. Natural- civilized human distinction, freedom, will, general will, categorical imperative, the kingdom of purposes, human dignity and equality are the prominent concepts in this connection. Some of these concepts, especially those which are associated with Kant, are evaluated in the context of his contributions to the ethical debates in Western philosophy. Despite such an evaluation, it is important to express Rousseau’s contribution to the emergence of these concepts through Kant’s ethics. The key ideas in this context are the contrast between natural and civilised humans, freedom, will, general will, categorical imperative, the kingdom of purposes, human dignity, and equality. Some of these ideas are assessed in the light of Kant’s contributions to the ethical discussions in Western philosophy, especially those which are associated with him. Despite this assessment, it’s vital to highlight Rousseau’s role in the development of these ideas through Kant’s ethics. In this regard, the first part of the study attempts to ascertain the degree to which Kant’s ideas on morality are influenced by the theories of the English moralists and Rousseau’s teachings, which are viewed as the two major ethical movements in Europe at the outset. Freedom, will, perfection, human dignity, and equality are fundamental components of human nature that define the line between nature and civilization. The problem of evil, which is a crucial issue in the ethics of the two names, and a similarity between Rousseau and Kant that is a little more challenging to discern have been attempted to be examined in the context of the Rousseauian effect in the third section of the study. It is noted that evil is seen as a result of freedom as in Rousseau according to whom started out from natural man with a synthetic attitude, besides touching upon the fact that civilization both corresponds to the fall of the natural man and is given as an explanation of evil, and that evil, like morality, is connected to the development of reason and sociality while Kant showed a progressive approach with an analytical attitude. It is highlighted that Kant agreed with Rousseau when he argued that by imposing the law onto ourselves, we become free and so develop morality. Additionally, while the writings of Kant and Rousseau are regarded as a primary source throughout the study, an effort has been made to draw on secondary works that discuss these two figures and highlight the relationship between these two names.