<p>Mercury (Hg²⁺) and lead (Pb²⁺) are among the most hazardous heavy metals, so effective monitoring systems for their detection in water are needed to protect environment and public health. This study numerically explores a dual-channel surface plasmon resonance (SPR) sensor based on a uniform-waist tapered optical fiber, designed to detect Hg²⁺ and Pb²⁺ simultaneously. Sensing channels are engineered with different thin-film metal coatings and optimized taper ratios. One channel incorporates MoS₂ over a silver film, while the other used graphene over gold, both utilizing the strong adsorption capability of 2D materials. The sensor’s performance is evaluated across a sensing medium refractive index (SMRI) range of 1.333–1.342. After structural optimization, the sensor is evaluated for the simultaneous detection of Hg²⁺ and Pb²⁺ ions within concentration range of 70 to 1000 ppm. The sensor achieved a maximum sensitivity of 0.0242&#xa0;nm/ppm for Hg²⁺ with a corresponding detection limit of 21.56 ppm, while the recorded sensitivity and detection limit for Pb²⁺ were 0.0251&#xa0;nm/ppm and 19.17 ppm, respectively. The proposed dual-channel tapered SPR configuration presents a compact, cost-effective, and highly sensitive platform for the detection of heavy metals.</p>