A new method for modifying electrodes with Ag nanoparticles (AgNPs) using electrospray deposition for sensitive, selective detection of Zn(II), Cd(II), and Pb(II) in aerosol samples when combined with Bismuth and Nafion coating and square-wave anodic stripping voltammetry (SWASV) is reported. Carbon stencil-printed electrodes (CSPEs) fabricated on a polyethylene transparency (PET) sheet were produced for an inexpensive, simple to fabricate, disposable sensor that can be used with the microliter sample volumes for analysis. Sensor performance was improved by modifying the electrode surface with electrospray-deposited AgNPs. The use of electrospray deposition resulted in more uniform particle dispersion across the electrode surface when compared to drop-casting. Using AgNP-modified electrodes combined with Bi and Nafion, experimental detection limits (LODs) of 5.0, 0.5, and 0.1 μg L−1 for Zn(II), Cd(II), and Pb(II), respectively, were achieved. The linear working ranges were 5.0–400.0 μg L−1, 0.5–400.0 μg L−1, and 0.1–500.0 μg L−1 for Zn(II), Cd(II), and Pb(II), respectively. Interference studies showed Cu(II) was the only metal that interfered with this assay but inference could be eliminated with the addition of ferricyanide directly to the sample solution. This electrochemical sensor was applied for the simultaneous determination of Zn(II), Cd(II), and Pb(II) within source particulate matter (PM) samples collected on filters using an aerosol test chamber.