Nowadays, the state-of-the-art discoveries in the field of delivery systems for therapeutic purposes have redefined the importance of biocompatible and biodegradable poly(lactic-co-glycolic acid (PLGA) nanocomposites. The study aimed to obtain a biocomposite material, with improved properties of its constituents [zinc-boron (Zn-B) complex and PLGA], by a simple, cost-effective method. The water∕oil∕water double emulsion technique allowed the adjustment of the synthesis parameters, to maximize the degree of Zn-B complex encapsulation. The morphological aspects of the samples were established by scanning electron microscopy (SEM). Particle size distribution was determined by dynamic light scattering (DLS). Morphology was typical for PLGA, spherical one. Depending on the synthesis conditions, the obtained particles have diameters between 10-450 nm. Zeta potential (ZP) showed that the particles have electronegative surface charge, offering a favorable perspective on aggregation, flocculation, and dispersion phenomena. It was observed, applying the design of experiments, that the particles size increased with increasing amounts of PLGA and polyvinyl alcohol (PVA), while ZP increased with higher PLGA and smaller PVA amounts in the formulation. The encapsulation efficiency was determined by ultra-high performance liquid chromatography∕mass spectrometry (UHPLC∕MS). The in vitro assessment was performed using Vero CCL-81 epithelial cell line and the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Zn-B-PLGA biocomposite has promising characteristics and can be used for future biomedical applications.