This study aims at first at the synthesis and the UV-visible, the infrared and the 1H Nuclear Magnetic Resonance spectroscopic characterizations of the 4-(dimethylamino)pyridine)[meso-tetra(para-chlorophenyl)porphyrinato]magnesium(II) with the formula [Mg(TClPP)(DMAP)].1/2C6H14 (I). The fluorescence and cyclic voltammetry studies have also been performed. The molecular structure of (I) was determined and described by single crystal X-ray diffraction analysis and Hirshfeld surfaces computational method. Complex (I) has a distorted square pyramidal geometry with a Mg__N(DMAP) distance value of 2.130 (4) Å and the average equatorial distance between the magnesium(II) central ion and the nitrogen atoms is 2.082 (3) Å. The crystal packing of our synthetic Mg(II) porphyrinic species is made by layers perpendicular to the [010] direction and the cohesion of the crystal packing is stabilized by nonconventional C–H···Cl and by C–H···Cg intermolecular interactions involving the pyrrole and phenyl rings of the porphyrin macrocycle. DFT calculations on (I) indicated an agreement with both UV-visible and IR experimental data. To gain further insights into the reactivity of (I), a density of states (DOS) and a molecular electrostatic potential (MEP) theoretical calculation were carried out. Furthermore, the antifungal and the antioxidant activities of the free base H2TClPP porphyrin, the [Mg(TClPP)] starting material and [Mg(TClPP)(DMAP)] (I) were also tested.