Hypoxic–ischemic brain injury (HIBI) is a major determinant of outcome after cardiac arrest (CA) and accounts for approximately two-thirds of deaths in patients who remain comatose after return of spontaneous circulation (ROSC), frequently following withdrawal of life-sustaining therapy (WLST) based on an anticipated poor neurological prognosis. Accurate neuroprognostication is therefore crucial to identify patients with potential for neurological recovery while avoiding premature pessimistic predictions. Current guidelines recommend a multimodal approach integrating clinical examination, electrophysiology, biomarkers, and neuroimaging. However, neuroprognostication is inherently time-dependent: HIBI is a dynamic process, and the prognostic value of individual markers evolves substantially during the hours and days following CA. Some markers may provide relevant prognostic information early after ROSC, whereas others achieve optimal accuracy only after 24–72 hours or later, as brain injury evolves and confounding factors progressively resolve. Thus, both the selection of prognostic markers and the timing of their assessment are critical to optimize prognostic accuracy. This review summarizes the temporal evolution of the prognostic performance of clinical examination, electroencephalography, somatosensory evoked potentials, biomarkers of brain injury, and neuroimaging after CA, and discusses how their integration according to optimal assessment windows may improve multimodal neuroprognostication and reduce prognostic uncertainty.