Prospective memory (PM) enables individuals to remember and execute future intentions, a function critical for daily activities such as replying to e-mails. This systematic review synthesises electrophysiological findings on event-based PM tasks in young adults, focusing on how cue nature affects behavioural performance and neural processing. Following PRISMA guidelines, 34 studies were examined to delineate common ERP signatures associated with PM cue processing. Embedding a PM task within an ongoing task (OT) consistently modulates neural activity, contributing to early occipital-parietal negativity (250-400 ms) that may reflect initial cue detection and sustained frontal and parietal positivities (200-1000 ms) linked to controlled retrieval and working memory updating. Notably, nonfocal PM cues produce enhanced and prolonged ERP effects, indicating greater demands on strategic monitoring and top-down control than focal cues, which favours spontaneous retrieval theoretical models. Comparisons between PM cues and OT trials further reveal that cues elicit additional early sensory processing reflected in larger frontal positivities and retrieval operations manifested by sustained parietal positivities. Focal cues tend to trigger a more transient retrieval process with shorter ERP components, whereas nonfocal cues produce enhanced and prolonged frontal and parietal responses. Moreover, factors such as cue frequency, salience, emotional valence, and language context modulate these neural responses, underscoring a flexible interplay between automatic and controlled processes. Collectively, these converging findings refine theoretical models - including the Multiprocess Theory and the Dynamic Multiprocess Framework - and advance our understanding of the neurocognitive mechanisms underlying PM.