BaAl₂O₄ nanoparticles were synthesized via a urea-assisted combustion route and systematically investigated to understand their structural, morphological, compositional, and optical properties. X-ray diffraction analysis (XRD) confirmed the formation of phase-pure hexagonal BaAl₂O₄ with high crystallinity, and the average crystallite size was estimated to be 25 nm. Scanning electron microscopy (SEM) revealed agglomerated nanoparticles with a porous morphology, which is attributed to rapid gas evolution during the combustion process. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of Ba, Al, and O without detectable impurity elements, indicating high chemical purity. Fourier transform infrared spectroscopy (FTIR) verified the formation of metal–oxygen bonds associated with the BaAl₂O₄ lattice. The optical band gap was determined using UV–visible diffuse reflectance spectroscopy combined with Kubelka–Munk and Tauc analyses, yielding a wide band gap of 3.85 eV. The results demonstrate that urea-assisted combustion synthesis is an effective route for producing nanocrystalline, phase-pure BaAl₂O₄ with controlled structural and optical characteristics. Owing to their wide band gap, porous morphology, and structural stability, the synthesized BaAl₂O₄ nanoparticles show potential for optical and photocatalytic applications.