Current therapeutic drugs for Alzheimer's disease (AD) can only offer limited symptomatic benefits and do not halt disease progression. Multitargeted directed ligands (MTDLs) have been considered to be a feasible way to treat AD due to the multiple neuropathological processes in AD. Previous studies proposed that compounds containing two aromatic groups connected by a carbon chain should act as effective amyloid β (Aβ) aggregation inhibitors although the optimal length of the carbon chain has not been explored. In the current study, a series of naphthalimide analogs were designed and synthesized based on the proposed structure and multiple bioactivities beneficial to the AD treatment were reported. In vitro studies showed that compound 8, which has two aromatic groups connected by a two-carbon chain, exhibited significant inhibition of Aβ aggregation through the prevention of elongation and association of Aβ fibril growth. Furthermore, this compound also displayed antioxidative activities and neuroprotection from Aβ monomer induced toxicity in primary cortical neurons. The results of the present study highlight a novel naphthalimide-based compound 8 as a promising MTDL against AD. Its structural elements can be further explored for enhanced therapeutic capabilities.