In this commentary, I examined the implications of Existentialism for science teaching and teacher education. Existentialist thoughts and premises can be used to explore the human element in an educational system. Before emphasizing the pragmatic and technical aspects of teaching, we need to rethink why we teach and recognize our learners as unique beings in a continual process of becoming. By incorporating the existential perspective into curriculums and pedagogies of science education, we can help learners to make their existences and experiences meaningful. This paper consists of three parts. In the first part, I drew on relevant aspects of Existentialism and its implications on the views of the learner. In the second part, I examined the competency-based curriculum in light of Existentialism. Existentialism aims, in part, to develop an educated person who possesses a clear sense of personal identity, a critical attitude, and the inclination to be a life-long learner, and so on. These characteristics are consistent with the implications developed from the competency-based curriculum. In the third part, I explored pedagogical activities consistent with existentialist thinking the ultimate goal of which is to create authentic individuals who can take responsibility for being humans. In the conclusion, I discussed how existentialist ways of thinking and teaching call for the science teacher's reflective practices, where the teacher needs to integrate personal and professional knowledge as the situation demands.