Silver nanoparticles (AgNPs) were synthesized in the pores of silica aerogel by supercritical deposition technique. The sample was impregnated with the precursor Ag(hfac)COD dissolved in supercritical carbon dioxide. Conversion was performed by laser irradiation at the wavelength of 405 rim, which matches the plasmon band of AgNPs. The synthesis process was visualized by measuring the extinction spectra in real time. We show that near-spherical AgNPs with the size of few nanometers can be synthesized fast and locally within the irradiated area of the sample. The concentration of AgNPs can be tuned by the time of exposition. The irradiation-assisted conversion is shown to be efficient both under supercritical conditions and after partial or complete depressurization.