Coal-measure soil slopes are susceptible to landslides, particularly with increased soil moisture. Traditional reinforcement methods, such as hot rolled ribbed bar 400 (HRB400), face challenges because of the high sulfur content in these soils, leading to accelerated corrosion and compromised stability. This study aimed to systematically evaluate the feasibility of using glass fiber-reinforced polymer (GFRP) and basalt fiber-reinforced polymer (BFRP) bars as sustainable alternatives to HRB400 for reinforcing corrosive coal-measure soil slopes. An integrated approach combining four laboratory tests simulating the high-sulfur environment (tensile, shear, creep, and corrosion tests) with two field tests (pull-out and long-term monitoring) was conducted to compare their performance. Laboratory tests showed that GFRP and BFRP bars possess elastic moduli over 50 GPa and tensile strengths exceeding 700 MPa, with tensile capacities 1.2–1.5 times those of equivalent HRB400 bars. In field pull-out tests, fiber-reinforced polymer (FRP) bars exhibited 13.4 %–16.2 % higher axial forces and 7.1 %–13.3 % higher ultimate pull-out loads compared to HRB400. Corrosion resistance tests further demonstrated the superior durability of FRP bars in acidic, alkaline, and saline environments, with BFRP showing a distinctive “decline-then-recovery” strength trend under prolonged acid exposure. Slope monitoring data confirmed that deformation remained within acceptable limits, indicating stable performance after reinforcement. This study provides, for the first time, systematic experimental and field evidence that GFRP and BFRP bars offer not only better mechanical and anchorage performance than HRB400 but also excellent corrosion resistance, making them suitable for reinforcing high-sulfur coal-bearing slopes. The findings present a sustainable and durable alternative for slope stabilization in similarly aggressive geotechnical environments, with both theoretical relevance and practical engineering implications.