Tissue engineering is constantly evolving towards novel materials that mimic the properties of the replaced injured tissue or organ. A hybrid electrospun membrane of electroactive poly(l-acid lactic) (PLLA) polymer with glass reinforced hydroxyapatite (Bonelike®) microparticles placed among the polymer fibres in a morphology like “islands in the sea” was processed. The incorporation of 60 to 80 wt% Bonelike® bone grafts granules with ≤ 150 μm into the polymer solution lead to an amorphous polymeric fibre membranes, and a decrease of the average polymer fibre diameter from 550 ± 150 nm for neat PLA down to 440 ± 170 nm for the hybrid composite. The presence of Bonelike® in the polymer mats reduced the activation energy for thermal degradation from 134 kJ·mol− 1, obtained for the neat PLLA membranes down to 71 kJ·mol− 1, calculated for the hybrid composite membranes. In vitro cell culture results suggest that the developed processing method does not induce cytotoxic effects in MG 63 osteoblastic cells, and creates an environment that enhances cell proliferation, when compared to the neat PLLA membrane. The simplicity and scalability of the processing method suggests a large application potential of this novel hybrid polymer-microparticles fibre membranes for bone regenerative medicine.