Surface-enhanced Raman scattering (SERS) is well recognized as a powerful analytical tool, enabling ultrahigh sensitive detection of analytes at low concentrations, even down to single-molecule level. Of particular note, in comparison to sufficient investigations on SERS-based detection of biomolecules (e.g., DNA and protein), there has been relatively scanty information regarding in vitro and in vivo detection. In this Article, we demonstrate a kind of SERS-active substrate, i.e., AgNPs-decorated silicon wafer (AgNPs@Si), as a high-performance in vitro sensing platform for single-cell detection of apoptotic cells. The AgNPs@Si yields highly reproducible SERS signals with an enhancement factor of ∼10(7). Remarkably, cellular experiments show that facile, noninvasive, label-free, and sensitive detection of apoptotic cells is readily realized using the high-performance SERS-active platform. Three kinds of apoptotic cells treated with apoptosis inducer are facilely and sensitively detected at the single-cell level, suggesting the exciting potential of AgNPs@Si for SERS-based in vitro analysis and detection.