‘Who am I really?’ When people ask themselves this question, they often find themselves in situations or dilemmas that may be labeled ‘existential’. They need to take an important decision, for example, and reflect on what is of fundamental importance to them. Also without explicit self-reflection, people’s behavior and experiences are influenced by what they care about most. Several philosophers have reflected on this existential aspect of selfhood. These days, cognitive neuroscientists too investigate e.g. love and self-reflection. What contributions to our understanding of the existential aspect of human lives can philosophy and cognitive neuroscience (CNS) make? I investigate existing CNS research into love and self-reflection and existing philosophies of existential selfhood, by Harry Frankfurt, Søren Kierkegaard and Charles Taylor, amongst others. I argue that CNS and philosophy are not in opposition with each other, as they address different types of questions. Moreover, CNS may benefit from cooperation with philosophy where reflection on moments of interpretation in its research process is concerned. I develop conceptual review as a tool to do so. I end with a philosophical view on existential selfhood and existential self-understanding that improves on existing philosophies and integrates insights from CNS where applicable.