In the present study, a new ion-selective imprinted polymer based on poly(methacrylic acid) loaded with 1-(2-pyridylazo)-2-naphthol (PAN) (IIP/PAN) has been synthesized, characterized and evaluated as a solid adsorbent for the preconcentration of Pb²⁺ with on-line determination by Flame Atomic Absorption Spectrometry (FAAS). For comparative study, a blank polymer (NIP) and IIP (imprinted polymer) without PAN were synthesized. The polymers were characterized by FT-IR and textural data through nitrogen adsorption/desorption measurements. Selectivity studies were performed by comparing the competitive adsorption of Pb²⁺ with Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺ and Zn²⁺ on IIPs and NIP, yielding relative selectivity coefficients (k′) higher for IIP/PAN than for IIP and NIP, which confirms the effect of PAN on the improvement of selective performance of IIP. Adsorption kinetic studies showed that the equilibrium adsorption of Pb²⁺ was reached at 100 min for the three polymers and its data were well described by pseudo-second-order and Elovich models. The maximum adsorption capacities (MAC) were found to be 41.4 mg g⁻¹ for IIP/PAN, 34.2 mg g⁻¹ for IIP and 30.1 mg g⁻¹ for NIP. The proposed on-line preconcentration method was based on loading 20.0 mL of Pb(II) solution (pH 5.70 buffered with 0.048 mol L⁻¹ acetate buffer) through 30 mg of IIP/PAN packed into a minicolumn at 4.0 mL min⁻¹ flow rate with further elution using 1.0 mol L⁻¹ HCl solution. The limits of detection (LOD) and quantification (LOQ) were found to be 0.52 and 1.79 μg L⁻¹, respectively, and linearity was from 1.75 to 200.0 μg L⁻¹ (r = 0.989). The precision of the method assessed in terms of repeatability was found to be 4.1 and 1.9% for 10.0 and 150.0 μg L⁻¹ Pb(II) solutions, respectively. The developed method was successfully applied to different kinds of samples (water, synthetic seawater, serum physiological solution, chocolate powder and Gingko biloba) and its accuracy was assessed by means of recovery tests and analysis of a certified reference material (MESS-3, marine sediment).