A sensitive, reliable, and environmentally friendly method for simple separation and preconcentration of Ag(I) traces in aqueous samples is presented prior to their flame atomic absorption spectrometric determinations. At pH 7.0, Ag(I) was separated with 2-(2-methoxyphenyl)benzimidazole (MPBI) as a new complexing agent and floated after adding sodium dodecyl sulfate (SDS) as a foaming reagent. The floated layer was then dissolved in proper amount of concentrated nitric acid in methanol and introduced to the flame atomic absorption spectrometer (FAAS). The effects of pH, concentration of MPBI, type and amount of surfactant as the floating agent, type and amount of eluting agent, and influence of foreign ions on the recovery of the analyte ion were investigated. Also, using a nonlinear curve fitting method, the formation constant of 1.62 × 106 was obtained for Ag(I)–MPBI complex. The analytical curve was linear in the range of 1.8 × 10−7–1.7 × 10−6 mol/L for determination of Ag(I). The relative standard deviation (RSD; N = 10) corresponding to 0.7 × 10−6 mol/L of Ag(I), the limit of detection (10 blanks), and the enrichment factor were obtained as 1.7%, 2.9 × 10−8 mol/L, and 43.0, respectively. The proposed procedure was then applied successfully for determination of silver ions in different water samples.