Because NK cells lack gene-recombination machinery and are thought to be relatively short-lived, it is unclear whether NK cells can mount long-term effective recall responses to reinfections by diverse pathogens. In this article, we report that FcRγ-deficient NK cells, which we recently identified and termed g− NK cells, possess distinct memory features directed by FcR-mediated Ab-dependent target recognition. The presence of g− NK cells was associated with prior human CMV (HMCV) infection, yet g− NK cell responses were not restricted to HCMV-infected target cells. In the presence of virus-specific Abs, g− NK cells had greatly enhanced functional capabilities, superior to conventional NK cells, and were highly responsive to cells infected with either HCMV or HSV-1. Remarkably, the g− NK cell subset persisted long-term at nearly constant levels in healthy individuals. Therefore, FcRγ deficiency distinguishes an Ab-dependent memory-like NK cell subset with enhanced potential for broad antiviral responses.