Gallium nitride (GaN) is an important semiconductor material with a wide bandgap, high breakdown voltage, and excellent optical properties. It is a necessity for optoelectronic and power electronic devices. In this research, the electronic and optical properties of GaN alloyed with aluminum (Al), boron (B), and indium (In) at 50% molarity were studied to explore the effects of alloying. The density functional theory (DFT) simulation was performed using Materials Studio (Castep), and it aims to simulate the structural, electronic, and optical properties of GaN alloys. Results show that by alloying, the bandgap is finely tuned, with Al enhancing it to 2.501 eV and In reducing it to 0.827 eV, while also creating strong lattice strain modulating the electronic structure. Ceramic phase stability, band structure, and optical properties such as absorption, reflectivity, and dielectric functions are analyzed, in particular demonstrating bandgap or absorption peak shifts and pronounced UV reflectance associated with alloying.