• Manganese-doped hydroxyapatite/polydopamine composites were successfully synthesized as microspheres with tunable manganese release and enhanced degradation rates.
• 5Mn-HA/PDA exhibited the strongest osteogenic differentiation and bone regeneration in vitro and in vivo among the tested materials.
• Polydopamine coating effectively controlled manganese ion release, reducing cytotoxicity while maintaining bioactivity.
• The composite material shows promise as a bone graft substitute for repairing critical-sized bone defects.