This article introduces the theory of cognitive spacetime. This account allows us to go beyond the space–time dichotomy that is commonly employed in psychology and cognitive science. Linguistic analysis and experimental review is provided to support the notion that what is commonly referred to as spatial cognition (or mental space) in the cognitive sciences always contains time, and that what is commonly referred to as temporal cognition (or mental time) always contains space. For “spatial cognition” the term object-spatiotemporal cognition (or object spacetime) and for “temporal cognition” the term event-spatiotemporal cognition (or event spacetime) is introduced. In order to exemplify the virtue of the new spacetime account (with its two subdomains, object spacetime and event spacetime) with a specific example, it is investigated how this new notion can substantially refine our understanding of space–time conceptual metaphor. A new conceptual-metaphor spacetime typology for cognitive processing underlying fictive motion and non-fictive motion is also proposed. Implications of the new spacetime account are discussed for metaphorically mapped mental perspective, metaphorically mapped embodiment, and cognitive science in general. Finally, specific reasons are given why the current proposal of cognitive spacetime cannot be equated with the concept of spacetime in modern physics.