Vertebral fractures are a common and severe consequence of osteoporosis, whose incidence is increasing due to population ageing. Current clinical management primarily relies on vertebroplasty and kyphoplasty, procedures that use bone cements to stabilize the fractured vertebral body and relieve pain. However, both techniques have limitations, including the risk of cement leakage. Injectable alginate hydrogels are emerging as promising materials for bone repair due to their ability to form hydrogels in situ under mild physiological conditions, working as a cohesive matrix for regenerative bone composites. Against this background, strain-promoted azide–alkyne cycloaddition (SPAAC) offers a cell-compatible strategy to engineer hydrogels with improved structural stability and tunable mechanical properties.?? Here, we developed a SPAAC-crosslinked injectable alginate hydrogel system and systematically optimized both the alginate functionalization and the crosslinking reaction.