BACKGROUND: Early detection and accessible monitoring of dementia are crucial for timely intervention. However, traditional neuropsychological assessments are resource-intensive, and with the growing aging population, scheduling delays increased. The Cogstate Brief Battery (CBB) offers a promising, rapid screening tool, though its validation in Mandarin-speaking populations has been limited. METHODS: This prospective, multi-center study assessed the validity of the CBB in distinguishing between mild cognitive impairment (MCI) and dementia compared to healthy controls (HC) in Taiwan. Participants from three tertiary medical centers underwent comprehensive cognitive evaluation using the CBB, including the Learning/Working Memory Brain Performance Index (Lrn/WM BPI), Attention/Psychomotor Brain Performance Index (Attn/Psychomotor BPI), combined BPI, and Brain Age. RESULTS: Of 192 participants (mean age 68.7 ± 8.2 years, mean education level 11.0 ± 3.9 years, 59.9% female), the CBB showed strong discriminatory power across groups. The combined BPI demonstrated the highest AUC (0.95) for distinguishing dementia from HC, followed by 0.92 for Lrn/WM BPI, 0.91 for Brain Age difference, and 0.88 for Attn/Psychomotor BPI. A combined BPI cut-off score of 41.25 effectively differentiated between HC and cognitive impairment groups. CONCLUSION: This first validation of the CBB in Mandarin-speaking populations highlights its utility as a reliable screening tool for early cognitive impairment detection. Its use could enhance timely diagnoses, helping to streamline clinical pathways and improve patient outcomes, addressing a critical gap in dementia care in Taiwan's healthcare system.