A geometric model is presented which unifies the three fundamental physical interactions: gravitational, electromagnetic, and weak. All of the indicated fields are unified on the basis of a single geometrical scheme – the geometry of a 5-dimensional metric-affine space-time with curvature, torsion, and nonmetricity. The initial Lagrangian of the proposed interactions unification model consists in one geometrical quantity – the scalar curvature 5R of five-dimensional metric-affine space-time. This initial Lagrangian L = 5R contains within itself a description of not only the three indicated fundamental physical interactions, but also the scalar Higgs fields which govern the induction of masses on the intermediate vector bosons – the carriers of the weak interaction.