Two types of alumina particles, commercial (c-Al2O3) and iron doped (Fe-Al2O3), were functionalized with 3-(aminopropyl)trimethoxysilane (one-step) and two-step consecutive process, i.e. firstly using 3-(aminopropyl)trimethoxysilane followed by methyl ester of linseed oil (biodiesel) to produce Al2O3ATPMS-BD reinforcement, respectively. The effect of modifier type and variable amount of alumina particles on the dynamical and mechanical properties of unsaturated polyester resin–based composites was studied. The highest improvement of the tensile strength and micro Vickers hardness, 78.1 and 163%, respectively, was obtained at 1.0 wt% of Fe-Al2O3APTMS-BD addition. The obtained multifunctional composites can be potentially applied in construction and mining industries.