Alzheimer's disease (AD) is one of the most serious health threats in our aging society. The major pathological feature of AD is excessive extracellular aggregation of β-amyloid (Aβ) protein in the form of Aβ fibrils or plaques. The simultaneous detection of Aβ fibrils and inhibition of their neurotoxicity is highly desirable for study of Alzheimer's disease. Although various fluorophores have been developed for imaging of Aβ fibrils or plaques, they suffer from serious self-quenching at high concentration and a lack of neuroprotective functions. To tackle these challenges, we herein develop a multi-functional probe of Cur-N-BF2 with aggregation-induced emission (AIE) characteristics for light-up detection of Aβ fibrils and plaques, inhibition of Aβ fibrillation, disassembly of preformed Aβ fibrils, and protection of neuronal cells. The AIE-active theranostic probe is thus promising for study of Aβ fibrils and plaques in Alzheimer's disease.