The development of synthetic bone scaffolds that mimic the composition and structure of natural bone remains a critical challenge in regenerative medicine. Calcium phosphate (CaP) nanoparticles, due to their compositional similarity to bone, have shown potential as functional components in bone tissue engineering, yet the influence of their crystallinity and carbonate content on osteogenic activity remains underexplored. In this study, flame spray pyrolysis (FSP) was utilized to synthesize CaP nanoparticles with controlled physicochemical properties, offering a scalable and industrially relevant approach for nanoparticle production. These nanoparticles were incorporated into poly(lactic-co-glycolic acid) (PLGA) fibers through electrospinning, forming composite scaffolds. The scaffolds exhibited significant biomineralization in simulated body fluid, promoting hydroxyapatite formation over time, independent of carbonate content or crystallinity. Pre-osteoblastic MC3T3-E1 cell studies demonstrated that the scaffolds supported cell proliferation and differentiation, with crystalline CaP nanoparticles (Ca/P = 2.19) yielding the highest alkaline phosphatase activity and collagen production. These findings highlight the potential of flame-made CaP nanoparticles integrated into electrospun fibers as a promising biomaterial for scalable bone tissue scaffold production.