Microheaters play a critical role in gas sensing applications, providing localized and controlled heating to enhance sensor performance. This work presents the design, fabrication, and characterization of a dual-function Titanium/Platinium (Ti/Pt) microheater integrated with GaN HEMT-based gas sensors. The device was fabricated using nanofabrication techniques, including photolithography, thin-film deposition, and lift-off processing, on sapphire substrates ensuring optimized thermal efficiency. Electrical and thermal characterizations demonstrated that the microheater operates stably up to 400°C with high reliability and reproducibility. The investigation into current densities further ensured that electromigration would not be a concern, confirming the long-term stability of the devices. These results highlight the potential of integrated microheaters in next-generation semiconductor gas sensors, offering improved selectivity, sensitivity, and stability.