This study presents a fiber-optic temperature sensor fabricated through controlled self-growth of a polymer microtip on the end-face of a capillary fiber. Optimization of the microtip parameters is achieved via theoretical analysis, establishing a robust framework for device reproducibility. The developed sensor exhibits notable advantages including simplified fabrication, cost-effectiveness, and high production efficiency, offering a promising alternative to conventional temperature sensing technologies. Experimental characterization demonstrates a linear temperature response within the environmentally critical 7–27 ℃ range, achieving a sensitivity of 0.175 nm/℃ through wavelength shift interrogation. Combined with its inherent corrosion resistance and compact design, this technology is ideally suited for long-term temperature monitoring in marine environments. The innovation addresses key challenges in marine sensing by enabling high-resolution thermal sensing.