To understand the impact of corrosion on metal on-shore buried transmission pipeline, which is one of the most critical damages, corrosion evaluation plays an important role. An effective approach for real-time in-line detection of corrosion is still not fully developed yet. This study introduces a concept of using an in-line optical fiber sensor system embedded inside metallic corrosion-resistant coating to conduct corrosion detection. Fiber Bragg grating sensors were selected as sensing units and the metallic corrosion-resistant coating was achieved using the high velocity oxygen fuel thermal spraying technique. The successful embedment technique was developed by using stainless steel adhesive protection during coating process. Accelerated corrosion tests were performed on four coated steel plate samples with embedded sensors. Both electrochemical and the embedded sensing system were used to assess the corrosion status of the samples. The test results proved the possibility of this method which can potentially apply for metal pipelines.