This paper reports our original technique for visualizing cell-attached nanointerfaces with extremely high axial resolution using homogeneously excited localized surface plasmon resonance (LSPR) on self-assembled silver nanoparticle sheets. The LSPR sheet can confine and enhance the fluorescence at the nanointerface, which provides high signal-to-noise ratio images of focal adhesion at the cell-attached interface. The advantage of this LSPR-assisted technique is its usability, which provides comparable or higher-quality nanointerfacial images than TIRF microscopy, even under epifluorescence microscopy. We also report the cytotoxicity of silver nanoparticles, as determined via morphological analysis of adherent cells on the sheet.