The tetragonal crystalline form of boron nitride remains in theoretical prediction stage till date without being synthesized in real practice and in accordance; properties could not be verified experimentally. Here we synthesize tetragonal boron nitride through a low-cost chemical synthesis route for the first time along with thermodynamic analysis and identification of evolved product gases through gas chromatography to authenticate the chemical reaction feasibility. The evolution of tetragonal boron nitride is substantiated with XRD analysis, Raman spectroscopy, x-ray photoelectron spectroscopy and FEG-TEM based SADP and EDS analysis together with IFFT micrograph-based measurement of the interplanar spacing of dominating (110) growth plane. The experimentally measured lattice parameters (a = 0.4378 nm, c = 0.2541 nm) closely match with those predicted theoretically (a = 0.4380 nm, c = 0.2540 nm). The presence of sp3 bonding in synthesized material is also confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy. Furthermore, we determine some significant properties of synthesized tetragonal boron nitride that envisage large optical band gap (5.66 eV), low electrical conductivity (671 S m−1) of semiconducting range, low density (1.83 g cm−3), high hardness (28 GPa) and the highest specific hardness (15.30 GPa/g cm−3) among other forms of polycrystalline boron nitride and commonly used hard ceramic materials. Accordingly, a new dimension is hereby added to material development for electronic/optoelectronic applications as well as in low-density hard structural material synthesis in view of using tetragonal boron nitride as reinforcement for metal matrix composites.