It can be said that the concept of Nibbāna has been spent various stages in its process and development in the nature of recognition. Therefore, it is necessary to examine the process of development of concept Nibbāna in main periods of Buddhism. It can be listed in four main periods of Buddhism: Early Buddhism, Buddhist Sect Period, Mahāyāna Buddhism and Vajrayāna Buddhism. Especially, with the development of Engaged Buddhist Movement, the concept of Nibbāna has been changed under the form of applied aspects. In this paper, various ways of understanding the concept of Nibbāna by modern engaged Buddhists such as Dr. Ambedkar, A.T. Aryaratne, Most Venerable Thich Nhat Hanh...etc. have been given in a possible way for a comprehensive recognition. The modern engaged Buddhists are chosen under the aspects of Buddhist schools. They are good exemplars in their respective traditions such as A.T. Aryaratne in Theravada tradition, Most Venerable Thich Nhat Hanh in Mahayana Buddhism, H.H. Dalailama in Vajrayana and Dr. Ambedkar in Neo Buddhism.