<p>Organizations often view mindfulness as a panacea for improving performance. However, this goal-oriented approach contradicts the non-judgmental attitude of mindfulness. Therefore, this paper seeks to clarify the essence of mindfulness through Eastern Buddhism, particularly Chinese Zen. This paper combines Zen Buddhism and the paradoxical perspective to develop the Paradoxical Theory of Mindfulness. The Two-dimensional Four-factor Model of Mindfulness reveals that the essence of the internal contradiction in mindfulness lies in the pursuit and abandonment of cognitive order between its two components: reflection and nonattachment. The Paradoxical Development Model of Mindfulness is used to explain how reflection and nonattachment can achieve mutual dependence despite their contradiction. Mindfulness entails the individual’s pursuit of cognitive order (lucid awareness) while accepting the disorder of outcomes (uncertainty). This article bridges the paradigms and contexts of Buddhist studies and psychology in mindfulness research, responding to the call for collaboration between science and Buddhism. The Paradoxical Theory of Mindfulness helps to better understand the complexity and richness of the connotations of mindfulness and returns to the Eastern tradition of mindfulness: the unity of opposites.</p>