Harmful algal blooms (HABs) increasingly threaten coastal ecosystems, aquaculture, and seafood safety worldwide, particularly in the Asia-Pacific region, where practical and environmentally sustainable mitigation technologies are urgently needed. Previous research developed DinoSHIELD, an alginate hydrogel-based biocontrol technology that immobilizes the algicidal bacterium Shewanella sp. IRI-160 or its cell-free filtrate, enabling the continuous release of bacteria-derived algicides that selectively inhibit dinoflagellates while limiting bacterial dispersion. Although effective against harmful dinoflagellates, the hydrogel formulation poses challenges for storage and transportation due to its high water content and mechanical fragility. To improve field applicability, DinoSHIELD prepared with cell-free Shewanella filtrate was fully dehydrated prior to application. The dehydrated formulation retained only 6% of the original hydrogel’s weight and volume, allowing storage at room temperature without a preservation medium. Laboratory bioassays demonstrated that the dehydrated DinoSHIELD retained algicidal activity comparable to the hydrogel formulation, effectively inhibiting the growth of toxic dinoflagellate Karenia brevis over five days. Its efficacy remained unchanged after four weeks of room-temperature storage, and the dehydrated beads maintained structural integrity in non-sterile seawater for at least 21 days. In addition, the dehydrated formulation showed no adverse effects on the non-target cryptophyte Rhodomonas sp., indicating that its algicidal specificity was preserved after dehydration. Ongoing studies are evaluating the dehydrated DinoSHIELD against major bloom-forming dinoflagellates in the Yangtze River Estuary, including Prorocentrum donghaiense, Karenia mikimotoi, and Akashiwo sanguinea. Together, these efforts aim to advance a field-deployable, environmentally sustainable biocontrol platform for HAB mitigation in Asia-Pacific coastal aquaculture systems.