Bone fractures are a common clinical event related to trauma, aging or diseases. Since bone repair is complex, abnormal consolidation may occur or, even, non-union. Biomaterials have a key role in this context, since they can stimulate bone cell differentiation, accelerating the healing process. Bioactive glasses (BG) represent a promising class of biomaterials due to its high bioactivity and osteogenic potential. Nevertheless, the osteoconductive properties of BG may not be enough to stimulate consolidation in critical situations. Thus, it was hypothesized that enriching BC with other materials such as collagen (Col) and magnesium (Mg), trying to make a composite with similar properties to bone tissue, would constitute a more suitable graft for tissue engineering. This work aimed at obtaining BG/Col/Mg composites and evaluating their physicochemical features. Moreover, 1.929 and MC3T3-E1 cell culture studies were done to investigate the cytotoxicity of the composites. The results showed that Mg could be successfully introduced, at different percentages (1, 3 and 5%), into BG and BG/Col composites, improving mechanical properties and retaining the bioactivity of BG. Ca assay measurements demonstrated that reactions in the Mg/solution interface, i.e. reactions between Mg and the ions in the simulated body fluid (SBF) have led to an increased Ca uptake for composites containing 3 and 5% Mg compared to plain BG and BG/Col. In vitro studies showed that BG and BG/Col containing 1% of Mg were non-cytotoxic and biocompatible. This percentage of Mg is promising for forward works. Our data on the present BG/Mg and BG/Col/Mg-based composites are encouraging and may lead to further molecular and cell culture studies, and in vivo investigations to clarify the biological performance of these new biomaterials.