Background: Huperzine A (HupA), a potent and selective acetylcholinesterase inhibitor with neuroprotective properties, faces significant clinical challenges in Alzheimer’s disease (AD) management. Its amphiphilic nature results in poor encapsulation efficiency within conventional hydrophobic polyesters or hydrophilic hydrogels, while its requirement for repeated dosing leads to systemic toxicity and poor patient compliance. Methods: We developed a novel hyaluronic acid (HA)-based biphasic delivery platform. This system utilized a HA gel matrix to encapsulate HupA-loaded polyhydroxyalkanoate nanoparticles (HupA@(NP/Gel)). Its sustained-release efficacy and therapeutic efficacy were evaluated in AD mice through a single administration, followed by behavioral, biochemical, and histopathological analyses. Results: The HupA@(NP/Gel) platform achieved complete drug encapsulation and successfully extended HupA release for over 20 days, matching the therapeutic requirements for AD. This sustained delivery translated to therapeutic efficacy in vivo: it significantly ameliorated core AD pathologies, including reduced Aβ deposition and restored cholinergic function. Moreover, the treatment conferred comprehensive neuroprotection by suppressing glial activation and neuroinflammation, enhancing neuronal survival, and preserving synaptic integrity. Crucially, these multifaceted benefits resulted in improved spatial memory and reduced anxiety/depressionlike behaviors. Conclusions: Our study demonstrates that the HupA@(NP/Gel) system can serve as an effective and translatable strategy for AD intervention. By effectively overcoming the key hurdles of HupA delivery, this work establishes a translatable sustained-delivery strategy that highlights carbohydrate polymer technology’s role in neurologic therapeutics.