This research work focuses on the fabrication and study of a series of nanocomposites consisting of two types of hydroxyapatite (HA), obtained by precipitate (HAP) and sol–gel (HAG) methods, and a boro-silico-phosphate bioglass. The microstructure and chemical, mechanical, and biological properties as functions of three factors, namely (i) the type of hydroxyapatite, (ii) glass content, and (iii) sintering temperature, were investigated. It was found that all of these factors affect the final composition and microstructure, especially, porosity, which shows significantly lower values for HAP-based composites than for HAG-based ones and higher values for higher glass content. This, in turn, has an impact on the microhardness, which exhibits a strong correlation with porosity, as well as on the mineralization capability and cell viability due to the different dissolution rate.