Black Powder is considered a severe hazard to the reliable operation of natural gas transmission networks globally. Hitherto, many corrective and preventive techniques have been proposed and demonstrated in the literature. Nevertheless, real-time detection of black powder in gas-carrying pipelines remains an open challenge. Real-time monitoring of black powder deposition in gas pipelines is crucial for ensuring a continuous gas supply to customers and making timely maintenance decisions. In this research, an all-optical technique is proposed in which multiple fiber Bragg grating-based sensors are optimally integrated into the gas pipeline’s inner wall to monitor the deposited black powder. Changes in the Bragg wavelength of Fiber Bragg Gratings (FBGs) due to the cumulative thickness of the deposited black powder are measured. The strain on the FBG sensors is analyzed to estimate the thickness of accumulated black powder in real time. The deployed FBG-based sensors exhibited a high sensitivity of 1.2 pm/µɛ and an R2 value of around 0.9975, exhibiting an excellent linear response of wavelength to strain.