Lead–acid battery recycling slags are important secondary resources because they contain recoverable Pb-bearing phases, while their improper management poses significant environmental risks due to the toxic nature of lead. This study investigated Pb recovery through physical pre-concentration and sulfidization-assisted flotation. The slag was characterized as an Fe-rich residue containing 40.1% Fe, 4.3% Pb, and 2.0% Ca. Size-by-size chemical characterization showed that Pb and Fe were broadly distributed among the particle size fractions, indicating that classification alone was insufficient for selective Pb enrichment. Shaking table tests produced partial Pb upgrading, with heavy products containing 10.3–11.0% Pb; however, low mass yields limited Pb recovery. Magnetic separation upgraded Fe-bearing phases to 48.5% Fe in the REMS magnetic product, but Pb was also recovered in the magnetic and middling products, confirming limited Pb–Fe selectivity. Flotation performance was strongly influenced by particle size, pulp pH, collector type, and sulfidization. Although the −0.2 mm flotation feed achieved the highest Pb recovery (71.5%) with KAX, the −0.1 mm flotation feed was selected as a finer feed to evaluate reagent effects under improved liberation conditions. Natural pulp pH (approximately 10) was adopted as the operating condition. Among the tested collectors, Aerophine 3418A provided the highest Pb recovery (83.8%). Sulfidization with 1000 g/t Na₂S further increased Pb recovery to 90.2% and reduced Pb distribution in the tailing to 9.8%. Overall, sulfidization-assisted flotation proved to be an effective approach for recovering Pb from Fe-rich lead–acid battery recycling slags.